The OTR a/c on our 4108 seems to be acting up. On the way out on our trip this weekend it took a while for the unit to start cooling where it was noticeable. Same thing happened a few weeks ago. Eventually it did okay and we were moderately comfortable inside the bus.
Coming home today with ambient temps hovering around 90 and with full midday sun, the temp inside the bus didn't get below 80 degrees. The compressor is running, the evaporator fan is running, and things look like they should. Problem is that the air is just not that cold.
My gut tells me that we've leaked somewhere and the refrigerant needs to be charged.
Any advice where to start the process? We have a 3-day drive to Wyoming in July, and having the OTR working by then will be a necessity to maintain domestic tranquility.
Buy refrigerant in 30 lb container and learn how to charge it. You'll be dealing with this as long as you have onboard air in an older coach. The newer models started using double or triple seals of more resistant materials. I would imagine getting a recharge done at a coach service place is going to be $250 or more. Btw, Luke does this if you are near NJ. Maybe a truck service plaza will do it also. Do you have the dual compressors?
Quote from: chessie4905 on May 28, 2018, 03:21:54 PM
Buy refrigerant in 30 lb container and learn how to charge it. You'll be dealing with this as long as you have onboard air in an older coach. The newer models started using double or triple seals of more resistant materials. I would imagine getting a recharge done at a coach service place is going to be $250 or more. Btw, Luke does this if you are near NJ. Maybe a truck service plaza will do it also. Do you have the dual compressors?
Neighbor just paid over $300.00 to fill a leaky 3T central air unit. 134a.
well the Home house protection plan did...
That was my gut thought... Low refrigerant. I thought that the tell-tale would come on and the compressor would shut down if that was the case though, which is why I was unsure. Maybe that's only if it's totally out.
We have the single compressor.
Anyone know which refrigerant this takes? I'm guessing whatever is most expensive. Can it be converted to the latest?
I just went through the receipts the PO gave me when I picked up the bus. He had it at Luke's for service.
Luke checked the OTR system and found no refrigerant. Ran a leak check and found no leaks. Refilled with 18 lbs of 134a. Cost was $504 for refrigerant, plus labor.
If he found no leaks, where did it go? Do leaks show up over the winter when things contract?
18 lbs of Freon went some where it has a leak.I have no idea how the HVCA works on a GM.one thing I do before I bring out the pump,gauges and Freon is check to be sure all the heat control valves are working proper,the AC loses the battle when in combat with the heater.I service a VanHool that is terrible about it and never needs Freon always a heat control valve
Biggest leak will be at compressor seal. They leak more if not in use for awhile. After filling, you can use some ref. leak liquid and check all the joints yourself. This is why most pull the onboard air when they convert them. Bus companies used to buy the freon in big oxygen style tanks. Learn how to add it and buy a 30 lb tank.
I bought a 30 # at Sam's Club 2 weeks ago for $118.99 in fact I bought 2
Correction to my previous post...
Apparently when Luke had the bus last summer they put in 18 pounds of R22, which is why it was so expensive. The bus definitely takes R22 and Luke confirmed that the price on the invoice was for R22. His suggestion was to take it in to have another leak test performed and then repair/recharge as needed.
I'd love to do this myself, but at the moment I don't have the necessary tools/skills to pull it off. Took the bus to a local shop that works on heavy road equipment and buses. They repaired the a/c on our 4106 in the past and seem to think that they can get this going as well. I hope so - guess we'll see.
BTW, I did a test this morning to verify that the problem was with the refrigerant and not that the water modulating valve was sending through hot coolant and creating a problem. I started the bus from a cold start and immediately engaged the a/c. The ambient temp was 82 degrees. The a/c was blowing 78 degrees. After the engine was fully warmed up the a/c was still blowing 78 degrees. Then I opened the cover over the heater core & evaporator coil in the HVAC bay and confirmed that the heater core was still cold to the touch. Unless I've missed something, this all points towards a problem with the a/c system itself, probably a low refrigerant level.
Anyone know what would trigger the a/c stop tell-tale on the 4108? On the 4106 it came on when the refrigerant was low. Either that's not the case here or the refrigerant isn't low enough yet to turn on the tell-tale. Or maybe the tell-tale system isn't working.
R22 is expensive I would check to see how much to convert over to 134A I did it on a Eagle I own and wasn't that bad something like 800 bucks ,then everything is expensive on a GM
Richard, if you check the sight glass on your liquid receiver tank after system is operating 30 minutes or more under maximum heat load, the liquid level should be in middle of sight glass.
According to the shop manual, 4108's didn't have the under dash evaporator or expansion valve. Maybe it was available as an option?
Quote from: chessie4905 on May 30, 2018, 04:01:25 AM
Richard, if you check the sight glass on your liquid receiver tank after system is operating 30 minutes or more under maximum heat load, the liquid level should be in middle of sight glass.
According to the shop manual, 4108's didn't have the under dash evaporator or expansion valve. Maybe it was available as an option?
My knowledge of a/c systems is minimal. I think I understand what the under dash evaporator would do (help cool the front of the bus) but I'm not sure what the expansion valve would do? And would either make a difference if the level of refrigerant is low?
The expansion valve regulates the flow of refrigerant through the evaporator coil. If yours has this core, it sit on top of heater core and is aluminum colored. About two inches thick. The expansion valve is of medium size and all brass. Can be seen in upper lh corner in compartment by entrance steps.
FYI....https://www.refrigerationschool.com/blog/how-to/r22-replacement-what-hvac-techs-need-to-know/ (https://www.refrigerationschool.com/blog/how-to/r22-replacement-what-hvac-techs-need-to-know/)
Richard -
I'm not sure, but I don't believe the 4108s had a "dash air" unit like the 4905s did.
I, too, think that your system is low on "freon", but not to the point it triggers the tell-tale.
FWIW & HTH. . .
;)
I think your freon is low as well. We switched over to 134A long ago. I have several cases of refrigerant and the discharge/recharge valves. It's much cheaper than R22.
I would be curious to know if you've checked the sight glass? I don't know about your insulation, but if the system managed 10 degrees, I would bet your seals are leaking.
I also don't know if you have Drivers AC/Heat, but if so, have you tried just the drivers AC? I usually average a small can every three years, and my first test is the drivers ac compared to the coach ac.
LOL he may be changing to 134,I was at the supply house a 30lb tank of 22 virgin (pure Freon) not the recycled crap was $879.00 a 10 lb tank cost $315.00 and a 1lb can cost $175.00 and they say it is going up every day
From what I read changing from R22 to 134 is not a simple process. Oil is not compatible, and many seals and other parts must be changed out.
Anyone changed a GM with a Frigidaire system from R22 to 134?
BTW, the prices you saw at the supply house are nearly identical to what Luke charged the previous owner to do the work last August. ($28/lb) Not sure about the 'going up every day' part.
Check the date on the compressor they started 20 years ago making the Carrier compatible with 134,oil is cheap so are the o-rings the dryer is little on the high side price wise and some hoses need to be changed FWIW Prevost was doing the change over for 3 k a few years ago and that is a high price shop.Drawing the system down to 30 is a challenge the H/F cheap pump dosen't cut it
There are better refrigerant drop in's to replace the r-22 in your use. You need to discuss this with Luke or another refrigerant service place or guy. Check on that compressor as a rebuilt to see what ref. it is then designed to use.
The source I supplied in upper post explains why R-22 is getting more costly and 2020 being the phase out date.
Here is what MCI changes when a refrigerant change is done.
http://www.mcicoach.com/service-support/serviceCoachExpress.htm (http://www.mcicoach.com/service-support/serviceCoachExpress.htm)
I would imagine Luke may charge 1500 to 5000 dollars to switch yours over. Of course, that depends on how complete a job he does.
Some places may just replace the o-rings, oil, flush system and refill with new ref. Back when we were converting r-12 to r-134, many were just throwing in the new ref. instead of doing it correctly. Some got away with cutting corners, some didn't. From looking online, it appears most are using the r-134 In any event, you should consider doing your own recharging, at least after changing over if you intend to maintain your otr ac system.
I know that there are a few alternative refrigerants to r22, and that some may or not be compatible with the equipment in this bus. It is all OEM and from 1974, and other than a leak somewhere in pretty good working order.
From what I've read in the past few days, 134 is NOT the ideal replacement for r22. It seems to be used often in place of r12, but not r22. I'll have to do some research on this.
For now, I'm hoping that the shop can locate the leak and then just refill. If Luke was unable to locate the leak last summer it must have been either tiny or in an out-of-the way area. Hopefully this time the shop here will be able to find it (and hopefully it will be something easy)
Like many others, our budget for this year is spent and I'm keeping what's left to fund any needed maintenance or repairs that need to be done over the next months. The bus was in great shape when we got it last fall, but it has been a heavy lift budget wise to get all the systems updated so quickly and get things ready for this summer's travels. I think that we've accomplished nearly everything on our list, and the things we couldn't get to are on the list for fall and early next spring.
From the MCI link, that is almost exactly what we did. But we also put in a new compressor.
Just a thought from the maintenance book...it says to use cold, no-pressure water and possibly aluminum cleaner for the condenser. It specifically says no steam cleaning, FWIW.
Quote from: richard5933 on May 30, 2018, 03:58:25 PM
From what I read changing from R22 to 134 is not a simple process. Oil is not compatible, and many seals and other parts must be changed out.
Anyone changed a GM with a Frigidaire system from R22 to 134?
BTW, the prices you saw at the supply house are nearly identical to what Luke charged the previous owner to do the work last August. ($28/lb) Not sure about the 'going up every day' part.
you won't buy virgin (pure) R22 today for $28/lb unless it is a 30 lb tank,the recycled sh** yea, EPA has shut the door on the cheap China and Mexico Freon.You buy a 30lb tank if you don't use it all it leaks out of the tank in about a year because of the cheap plastic valve they install on the tanks I cap my tanks and still loose the Freon .These low end tour operators from Mexico and the US too you can walk by one and smell the Propane they use in the systems how stupid is that.Richard to get a handle on the your deal just call Welch in Ga he can answer any questions you have about AC in a bus
Quote from: luvrbus on May 31, 2018, 05:50:35 AM
you won't buy virgin (pure) R22 today for $28/lb unless it is a 30 lb tank,the recycled sh** yea, EPA has shut the door on the cheap China and Mexico Freon.You buy a 30lb tank if you don't use it all it leaks out of the tank in about a year because of the cheap plastic valve they install on the tanks I cap my tanks and still loose the Freon .These low end tour operators from Mexico and the US too you can walk by one and smell the Propane they use in the systems how stupid is that.Richard to get a handle on the your deal just call Welch in Ga he can answer any questions you have about AC in a bus
The shop that has the bus to do the work does a/c work for many of the charter companies around here. I have to assume that they are buying it in 30 lb or larger sizes.
Good news and bad news...
Good news is that the shop says they found the leaks and the problems. Apparently the compressor was leaking out the end, the dryer is bad/leaking (not sure what he said), and there is one other part needing replacement (I think he said evaporator valve or expansion valve but not sure). Right now it's a waiting game for the parts department to hunt down the necessary parts and put together the estimate. Once I see that I will know specifically what the problems are. I did provide them with a service manual, a parts manual, and Luke's contact information to help them get what they need.
Bad news is that they found the leaks and the problems. Looks like I'd better get ready to let the cash begin flowing...
I've asked them to let me know how much more it would be to change to a newer refrigerant at this time since we're going to change the compressor. The service desk guy's initial gut reaction was 'that would be much more'. Won't know for sure till they get it figured out. Of course, if they did find the leaks then perhaps it will buy us a few years of service on the current a/c??
Sounds like this is one of those times we're going to have to pay for the privilege of owning a bus with so few miles, since lack of use may have starved the parts of the needed lubrication, causing things to go bad. Just a guess. Glad I held back some cash for things that pop up.
And yes, I'm still wanting to keep the OTR a/c functional. We've got two basement a/c units and a generator, but I'm sure you've already read that those aren't all seeing eye-to-eye right now. If we have to replace the basement units at some point, we're considering installing two roof-top units and a dedicated 24v inverter which can run them while on the road. That's for a much later time though.
Road air is expensive to keep running it buses,it would be hard for me to give up a road air that just needed a few repairs,sounds like the R22 is going to be the cheap part of that repair Richard good luck
Quote from: richard5933 on May 31, 2018, 01:22:56 PM... I'm still wanting to keep the OTR a/c functional. We've got two basement a/c units and a generator, but I'm sure you've already read that those aren't all seeing eye-to-eye right now...
Sorry about the bad news parts. Is there any chance you can get the basement a/c units rehabbed for not much $$$. If possible, that might be a good stop-gap. Best wishes with the next parts in this process.
Quote from: Oonrahnjay on May 31, 2018, 08:13:00 PM
Is there any chance you can get the basement a/c units rehabbed for not much $$$.
Define not much $$$. :)
I said to heck with it and had new compressor, new evaporator, condensate drain tray, dryer, acid flush, and recharge done on my 22 year old 3T basement air 3 years ago. It was limping, mostly because the condensate tray (metal) was leaking inside the bus and the compressor was hitting mucho amps to start (had hard start caps, ate a start cap, run cap was fine),and and and..it was worn...But I am confident that my $1600.00 will get me to end of life for this bus...AND the day is coming that no amount of money will get you R-22 parts in the USA. If you can fix what you have do it :)
Granted it wasn't OTR, but it wasn't cheap either...
Quote from: eagle19952 on May 31, 2018, 10:30:23 PMDefine not much $$$. :) ...
Yeah, that's big the issue. But Richard was saying that availale $$$ right now is a major consideration. It's all a balanced juggle -- and probably one of those things for which there is no good answer.
To be honest, my big worry right now is just parts availability. I'm not sure if the compressor, etc., that they need can be found. To me it doesn't seem like a compressor, dryer, and assorted parts should be hard to find, but I'm only guessing.
Maybe the situation isn't as bad as could be...
Apparently the problem with the compressor is a leak at the front seal, or at least that is the working theory. Luke's got replacement seals available. The tech working on the bus at the local shop doesn't feel comfortable doing the seal replacement, so they are going to r/r the compressor and send it to Luke's shop in NJ to have the work done. Sounds like most of what they work on at this shop just gets new parts, as most of the newer systems are not designed to be rebuilt and/or resealed. Their tech has not been trained to replace seals in compressors and doesn't believe he's got the correct tools to do it properly.
Although it will add a few days to the work for shipping back and forth to NJ, I'm really glad that they acknowledged up front their limitation instead of attempting to do the work and damaging the compressor. To me this is a sign of a good shop and makes me feel better. I'm also happy that they are willing to have me settle up with Luke directly for his work instead of up-charging the whole thing.
So, at the moment the extent of the problem seems to be limited to the leaking compressor seal, a bad dryer, and a failing electrical plug. And of course replacing the r22 that escaped when things went bad. Not nearly as bad as it could be and hopefully will enable us to keep the thing cool and comfortable for at least a few more years.
What model is the compressor a 05G ?
Quote from: luvrbus on June 01, 2018, 12:04:07 PM
What model is the compressor a 05G ?
To be honest, I have no idea. It's a Frigidaire, but that's as far as I can say with certainty.
I'd look it up in the manual/parts book but they're in the bus at the shop. Regardless, I'm assuming that Luke and Bill will be able to replace the seal and put Humpty Dumpty back together again.
That is old 3 cylinder Frigidaire,hopefully for you the seal carrier is not bad and a seal will fix it, they are a bear to make stop leaking even for a year
Quote from: luvrbus on June 01, 2018, 12:35:42 PM
That is old 3 cylinder Frigidaire,hopefully for you the seal carrier is not bad and a seal will fix it, they are a bear to make stop leaking even for a year
You're not making me feel better here...we need happy bus thoughts.
Luke seemed to have confidence that they could get it going. Guess we'll see. I'm sure that I'll be addressing this again in the future. Maybe by then I'll have a plan for moving forward with a new and more modern refrigerant. I'm hoping that with regular use it will do better than it did sitting for most of the past 44 years in storage and maybe least at least a while.
LOL the only happy thoughts about owning a bus come from the people there to help empty your wallet ;D
Quote from: luvrbus on June 01, 2018, 12:04:07 PM
What model is the compressor a 05G ?
Now that I've seen pictures of an 05G, I can say for sure that's not it. Looks like an A6 compressor, although I'm not sure if there are other models with the same look. The book does state that it's a 3-cylinder rotary, so the A6 is at least in the right family.
Either way, the compressor is on its way to Luke as we speak and hopefully he and Bill can work their magic on it. Doesn't sound like there was much wrong besides the compressor leak and the bad dryer, so I'm still hopeful.
Funny note...the guy from the shop here was apologetic when I asked him if there were any surprises after they pulled the compressor. He said that the only surprise was the price on the r22, which he hesitated to tell me. It was actually less than Luke charged the PO when he worked on the bus last summer, so I am guessing it's been a while since the local guy had need to order a tank.
I sounds like he had to order a 28-lb tank to get enough to fill the bus' system, even though we only need 22 pounds. Hopefully he'll charge me for what he uses. Otherwise I guess I'll own an extra 6 pounds of r22.
hopefully, (and I'm not trying to rain on the parade) after the biggest leak is fixed there are no little one that rear their ugly heads.
Yeah - they warned me about the possibility of other leaks being found once the system was up to full pressure. Hopefully if there are additional leaks they will be confined to simple things like o-rings or the like.
Usually when you have leakage issues, they charge the system with nitrigen to about 70 to 100 lbs and start checking with leak test fluid. After repairing any leaks found, they recharge with nitrogen and leave it sit overnight to see it it drops any.
On my 1991 Prevost going through the same deal. Bought another rebuilt compressor (O5G Bus) and going back after testing with Nitrogen, Will replace dryer and hope for the best if pressure holds. Think you can buy all the goodies on all, if your pockets are deep enough. Oh and Cliff Prevost (Ft. Worth and Houston) told me $10,000 labor , plus parts to get mine up in shape. Could be $15 to $20,000. :o It ran for year after converting to R134 and compressor seal started leaking last year. At first twice a year recharge and then after one trip it would leak out.. You know it leaking as you can see the oil behind pulley's on compressor. Have to change unloaders out as new compressor has electronic ones.
These issues are why most say to ditch the otr ac when converting an older coach. The newest models have robust sealing due to the fed. regulations about ozone protection.
Quote from: chessie4905 on June 04, 2018, 06:20:10 PM
These issues are why most say to ditch the otr ac when converting an older coach. The newest models have robust sealing due to the fed. regulations about ozone protection.
All the new units are double seals,Prevost told 10,000 for labor on what Glen converting to R134 ?
Prevost coaches must have a much more robust and/or complicated system. Or perhaps there was lots more wrong with things. Either way, my worst-case scenario is nowhere near that expansive. Right now I'm in for about about $600 for the r22 and a few hundred more for the seal kit & installation. They've estimated 12 hours labor for the whole job including if they find a few more small leaks. Of course it could go up from there, but I'd have a long way to go to reach $10K.
Don't know if I'd break the bank to keep the OTR working, but I haven't seen a replacement plan that is as simple to use as OTR and that provides as good a result. Regardless, for now we've made the decision to try and keep the system running. Over the next year I'll be exploring options for upgrading the refrigerant to something that can be replaced moving forward as r22 is phased out.
If you continue to have some leak issues, you'll wish you would have bitten the bullet now and converted to R 134. A lot of the Prevost cost will be to upgrade to better hoses. The molecules of R134 are much smaller and can pass slowly through the old hose material. Plus some pressure control units need replaced due to operating characteristics of 134 vs. 22.
Quote from: chessie4905 on June 05, 2018, 03:50:57 AM
If you continue to have some leak issues, you'll wish you would have bitten the bullet now and converted to R 134. A lot of the Prevost cost will be to upgrade to better hoses. The molecules of R134 are much smaller and can pass slowly through the old hose material. Plus some pressure control units need replaced due to operating characteristics of 134 vs. 22.
I did ask about the conversion, and apparently 134 is not a viable replacement for r22. The pressure differences are too great, from what I understand. There are a couple of r22 replacements in use for home a/c systems, and I'm hoping that before it's needed in our bus they'll get something that works reliable in the system.
The only hoses I see in our system are those that are between the compressor and the copper tubing. Both the condenser coil and the evaporator coil appear to be mounted with sweated on copper lines.
If you've got some information about using 134 to replace r22 I'd love to see it, as so far nothing I've found makes it seem doable in a simple method.
The reason the Prevost deal is so expensive is they change/replace everything even the Compressor, Expansion Valves and all Hoses, even if you have put the right kind on for R134. A complete system change out. From front to back. The Condenser side to Evaporator side across coach is a biggie they said as they might have to pull tanks out as the hoses go across. They Say that's the only way they can warranty it for a year. Yeah, like I would believe that.
Quote from: muldoonman on June 05, 2018, 04:37:50 AM
The reason the Prevost deal is so expensive is they change/replace everything even the Compressor, Expansion Valves and all Hoses, even if you have put the right kind on for R134. A complete system change out. From front to back. The Condenser side to Evaporator side across coach is a biggie they said as they might have to pull tanks out as the hoses go across. They Say that's the only way they can warranty it for a year. Yeah, like I would believe that.
Naw that is another Prevost way of saying we don't won't to fool with it at one time it cost 3 to 4 k at Prevost in Ca of all places
Yes, thats something nice about GMs, they did it without a lot of hoses. The other brands never figured that out.
I don't blame Prevost, as they are a premium brand, at least to many that aren't necessarily on this board. They are going to insure you get a solid issue free ac upgrade. I don't care for that price, but do the labor yourself and save a lot of those bucks.
As earlier in a reference given, there are other refrigerants that will work in r22 systems that don't harm the environment, but I don't know what price/lb.
Many bus companies and manufacturers felt r134 could be compatible with their systems,and considered the ample availability of the r134.
The outfit servicing your 4108 may not want to get into changing refrigerant issues.
Gm sure used a funky design with the clutch and drive though,I doubt any updated compressor will fit or work besides the Frigidaire in that space ,I always believed the drive design was the cause of the seal failure on the GM buses that is a tough seal to to prevent from leaking over time,back then r 22 was cheap you just kept on adding Freon it wasn't a big deal
Here's a picture of the compressor. (https://uploads.tapatalk-cdn.com/20180605/ddfe2bf5198a0e91f97166f99e08e20a.jpg)
Is there only one? GM book lists a dual a6 design. Maybe the 4108 only needed one. That is a larger model of the one GM used in cars for years and years. Other than seal leakage, it was pretty much bullet proof. They did have a tendency to leak from lack of use. The other design in the coaches was a bigger v type that ran from a driveshaft off front of engine. They had a clutch to operate it. Drivers were cautioned to never engage it above idle or it would tear up clutch eventually.
Do a google and see if anybody rebuilds it to r22 or other specs.
We've got just the one. Section 26C of the maintenance manual shows this option. There was another option with dual compressors, but this coach did not ever have that dual option. I'm assuming that being sold originally in the NJ area there was not felt to be enough need for that.
I'm hoping that you're correct about the bullet-proof part, and that once Luke & Bill install the new seals we'll be good to go. This a/c compressor definitely did not get very much use and sat for substantial amount of time without running the a/c. We're rooting for that the be the cause.
That is strange Bill's 4905 has a 4 cylinder aluminum Frigidaire V type AC compressor just like the one used in the GM transit buses. I know the transit buses used it because I bought one from a GM transit for his, the clutch looks like a mushroom type clutch and it is factory AC when it works
Quote from: luvrbus on June 05, 2018, 12:23:59 PM
That is strange Bill's 4905 has a 4 cylinder aluminum Frigidaire V type AC compressor just like the one used in the GM transit buses. I know the transit buses used it because I bought one from a GM transit for his, the clutch looks like a mushroom type clutch and it is factory AC when it works
Strange good, I hope.
Our old 4106 actually had something similar to this compressor, only it had two of them. They were installed in place of what was OEM for the 4106. From the little I know about these things, this type of compressor is pretty good and can usually be re-sealed with success.
That compressor was the work horse for years,you got to watch the oil though they won't handle many Freon charges without adding oil or they seize up,I am sure your AC guy will know how much oil it will take for your system which is going to be more than a average car
Got an update from Luke. Apparently there is something wrong with the compressor shaft, and after two seal kits they cannot get the compressor to seal and hold pressure. Not good news. Luke is out of town till Tuesday, and when he gets back he is going to try and find a replacement compressor.
My parts book is in the bus at the shop. Anyone know what the part number is on this type of compressor? I'd like to do some reading on the compressor but can't find anything online without a part number or model number on the compressor.
Hopefully Luke will be able to come up with a replacement compressor, or another compressor that can be made to work. If not, I'll be looking for a 'B' plan to keep the OTR running. Seems to me that since the only function of the compressor is to pump refrigerant, there has to be something else out there that can do the job if this particular compressor is NLA. Fortunately the a/c compressor is the only thing on the belt, and there is lots of room in the area to accommodate options if one can be found.
Still want very much to keep the OTR in place, since the alternative to stay cool on the road would involve a better house a/c system as well as a better generator. I wouldn't want to run the old Perkins that many hours, both due to its age and the high fuel consumption, and the current basement a/c units would have trouble keeping the front of the bus comfortable on sunny days.
Call Welch Industries in GA 770-474-1150 he is the bus AC expert and he will have a replacement
Quote from: luvrbus on June 06, 2018, 02:15:05 PM
Call Welch Industries in GA 770-474-1150 he is the bus AC expert and he will have a replacement
Do you know what the compressor's model number is? Or, would they be able to look it up by the coach's model number?
Looks to me like an A6 compressor, but boy oh boy are there a lot of variants out there. Switch type, CCW vs CW, 12v vs 24v, pulley type, pulley size, etc, etc.
I'm going to let Luke attack this one when he gets back, since he has the know-how and experience to get the right one. That is, unless someone just happens to have a working a/c compressor off a 4108a sitting around that needs a good home.
At least there are lots of places still selling the compressors, and while not cheap it's still going to be less than the refrigerant going into it.
From my 4905, 4108 shop manual:. Refrigerant compressor Frigidaire 6 cylinder axial 12.6 cu. In. Rotation veiwing drive end counter clockwise GM part number 5910771.
12 volt clutch coil.
Where do they pick up the 12v for the clutch on a 4905
4905 uses a big v type compressor running off a driveshaft from front end of engine. Comes off at an angle and clutch is air operated.
The dual A-6 option is belt driven and both compressor clutch units are rated at 12 volts. Wiring diagram shows them wired parallel, so I don't know if coil voltage rating is a typo or it doesn't care.
Apparently since the 4108 doesn't have a dash evaporator, it gets by with the single compressor.
Thanks for the information and confirmation that I was looking at the correct data, especially the part about the 12v clutch. After looking at the various listings online, the hard part looks like it's going to be finding the CCW rotation.
The A6 compressors in the online catalogues all list either r12 or r12/r134 as the compatible refrigerants. None that I've found show r22 as compatible. Is that simply because no one is running r22 so they don't show it, or is there a physical difference in the compressors used for r22? They look to my eye to be the same, other than possibly the oil being used.
Our 4106 had been converted to r134 at some point, and the only piece of hardware that I knew to have been changed was the compressor. Since we are going to be changing the compressor on this bus now, what would be the result if the refrigerant was changed and we left the condensing coil and other hardware in place? The rubber lines to the compressor have been mentioned as possible problems, anything else? What about functionality? Will the other components still produce cold air or am I going to need to change other things?
Or, is my original plan of just replacing the compressor and refilling with r22 the best working plan at the moment.
What's killing me here is actually the amount of time this is taking - weather right now is gorgeous and I really want to be on the road. But, we are planning to drive to Gillette WY in July though, so we'll need the a/c working by then and this is as good a time to deal with this as any.
If you are replacing compressor anyway, it would be foolish to stay with R-22. The newer rebuilds MAY have more robust seals made from compatible material.
I suspected this but decided to verify. Your compressor, due to its design can operate in either direction.
https://www.powernationtv.com/post/different-model-ac-compressors-and-how-they-work (https://www.powernationtv.com/post/different-model-ac-compressors-and-how-they-work)
Outlet and inlet ports should be same size.
This gets more confusing every day. Luke was not able to get a replacement compressor through his usual channels. Apparently the hang up is the CCW rotation. The part number we're looking for is 1131207, which is an A6 Frigidaire compressor with a 5.5" clutch, 12v, CCW, with type C ports.
I was able to find one which is nearly the same as what is in the bus, but with two minor differences. At least I hope they are minor.
The one I'm looking at is: https://truckerac.com/gm-compressor-model-a6-type-c61138002.html
The two differences are that the new one has a 6" pulley instead of the current 5.5", and the new one is filled with PAG150 oil instead of the mineral oil which is in the current one.
The pulley size doesn't seem that big a deal. Seems like it would spin slightly slower, which might create a problem at idle or low speeds, but I'm thinking that at highway speeds things should be okay.
The oil is what I'm more worried about since I don't think that the PAG150 is compatible with either the r22 or the current mineral oil. I'm hoping that it's possible to flush the PAG150 out of the compressor before installing it and then refill with the mineral oil.
Anyone able to shed some light on these two issues?
In reply #65 and again here, the A-6 can be run either direction without changes.
http://www.refrigeration-engineer.com/forums/archive/index.php/t-40024.html (http://www.refrigeration-engineer.com/forums/archive/index.php/t-40024.html)
It's not the turning direction of the compressor it's the clutch engagement and I have no idea how you solve that on a A-6 compressor
I bet AP Air in IA will have what you need 800-806-5312,be for warned they can be a bitch to convince to sell to a individual but will come around most of the time
Quote from: luvrbus on June 12, 2018, 08:48:38 PM
I bet AP Air in IA will have what you need 800-806-5312,be for warned they can be a bitch to convince to sell to a individual but will come around most of the time
I'll call them in the morning.
Quote from: luvrbus on June 12, 2018, 08:01:17 PM
It's not the turning direction of the compressor it's the clutch engagement and I have no idea how you solve that on a A-6 compressor
Not sure what you mean here. The clutch seems to engage by pulling along the axis of the main shaft. My concern about the clutch was the diameter being 6" instead of 5.5" as was originally in the bus.
Quote from: chessie4905 on June 12, 2018, 07:37:54 PM
In reply #65 and again here, the A-6 can be run either direction without changes.
http://www.refrigeration-engineer.com/forums/archive/index.php/t-40024.html (http://www.refrigeration-engineer.com/forums/archive/index.php/t-40024.html)
That's not what I'm being told. The A6 is sold in both versions, CW & CCW. If they could turn either way, the specs wouldn't include rotation. The guy at Welch in GA told me that the oil pump is different on the two rotations, and that spinning them backwards will make cold, but the oil won't circulate and the compressor won't last last long running backwards.
Clutch engagement? The electrical coil pulls the clutch plate in against the armature, causing the pulley to turn the internal components. Direction of rotation doesn't matter. It's just like the car model GM made, only larger. They reverse the inlet and outlet connections on the rear.
Quote from: chessie4905 on June 13, 2018, 02:29:02 AM
Clutch engagement? The electrical coil pulls the clutch plate in against the armature, causing the pulley to turn the internal components. Direction of rotation doesn't matter. It's just like the car model GM made, only larger. They reverse the inlet and outlet connections on the rear.
Like I said, I did find one that is built to spin CCW as I need, but has the 6" clutch and the wrong oil. Any idea if this one can be made to work by flushing/changing oil and using a larger belt?
Not sure how much of a difference the 1/2 diameter difference will make in performance and can't find anything online with charts or other information.
Quote from: chessie4905 on June 13, 2018, 02:29:02 AM
Clutch engagement? The electrical coil pulls the clutch plate in against the armature, causing the pulley to turn the internal components. Direction of rotation doesn't matter. It's just like the car model GM made, only larger. They reverse the inlet and outlet connections on the rear.
I have come across magnetic clutches the lining are made to engage right or left on equipment and they come apart if wrong.I have a GMC the friggin fan spins backwards through a magnetic clutch figure that one out
Quote from: luvrbus on June 13, 2018, 05:33:48 AM
I have come across magnetic clutches the lining are made to engage right or left on equipment and they come apart if wrong.I have a GMC the friggin fan spins backwards through a magnetic clutch figure that one out
Can't figure that out any more than I can figure out why GM used a 12v clutch in a bus with a 24v electrical system.
The A-6 uses metal to metal clutch engagement, with no clutch lining involved.
Richard, If Luke changed front seal, he had to remove pulley and clutch. He should be able to swap pulleys.
The replacement compressor you listed is metric threads. Luke will have to substitute metric bolts for the us or sae. ones.
The replacment compressor has that oil so it can use r-134, according to the specs. Good time to switch over.
I appreciate all the comments on this thread about the a/c problems. We've made a few decisions and have ordered the compressor. It is going to be a bolt-in job with the two exceptions I wrote about earlier...The clutch is 6" dia instead of 5.5", and the oil is PAG instead of mineral oil.
The tech at the shop (and the tech at the compressor place) don't think that changing the oil to mineral oil will be a problem, but it might take a few fill and drain cycles to get it done. They are going to change the oil in the compressor before it's installed to avoid getting the oil in the system contaminated.
The clutch/pulley dia will likely not be a problem, assuming that there is enough adjustment in the mount to put the belt on and/or a larger belt can be found. There is a slight possibility that the smaller clutch/pulley and slower spin speed could result in insufficient cooling, but the tech at the shop doesn't feel it will be a problem except possibly at very slow-speed driving. If it is a problem, we could always swap our current clutch for the new one.
The shop is aware of the change to metric mounting bolts - I'm going to have to assume that they can manage that. If not, we have bigger problems.
We opted to not change refrigerant at this time, for a couple of reasons. The main one was that there was no real way to be certain that it would have adequate capacity to keep the bus cool after the switch, especially since our bus just has the one compressor and not the dual compressor option. There was also a question about how the rest of the system would perform with another refrigerant. The tech at the shop says that over the next year new formulations should be coming online that can be used to better replace the r22 that's in there currently. The r143 is used to replace r12, but it has much less cooling ability than the r22, or so I'm told. Either way, if we decide to switch it won't be that much more difficult later on than doing it now, we'll just have to switch oil again.
That's all I know right now. As things arrive to the shop and get installed I'll update. Hopefully someone else can learn from all this.
Everyone keep thinking happy cool bus thoughts...
I don't think the pulley will make that much difference AC compressors run 1:1 to !:4 of the engine speed last I heard
I doubt it also.
Update...
After a long series of problems locating the compressor, shipping issues, rain delays, and scheduling issues at the shop we are finally making progress on this. Only two parts were needed - a compressor and a drier.
The compressor has been installed. There was more than enough play in the bracket to allow the existing belt to be used. The new drier was installed, and the compressor has been connected to the hoses. That's all good news.
When I stopped in at the shop at noon the mechanic was getting ready to charge the system with nitrogen/dye to test the system. I just checked with the second shift service writer this evening, and he says that the notes indicate things are still underway and moving along. Since the mechanic doesn't work Fridays, I guess that it will be Monday till I know more. Not sure if there were additional leaks or problems identified after I left the shop. Hope not.
The waiting and waiting is really starting to get to me. Always seems to be that something like this will happen right at the time of the year I want to be on the road.
Quote from: richard5933 on June 21, 2018, 04:15:24 PM
Update...
The waiting and waiting is really starting to get to me.
the wait is worth it when the job is done right :)
Quote from: eagle19952 on June 21, 2018, 04:51:13 PM
the wait is worth it when the job is done right :)
Very true!
And sometimes you get a pleasant surprise, like the phone call I just got from the 2nd shift service writer. Apparently the tech is coming in tomorrow to try and finish the job for us this week, even though it's normally a day off for him. Sounds like the hangup today was just how long it's taking for them to properly evacuate the system, do a final leak check, and then refill with the r22. The guys at Lakeside International in Milwaukee are definitely going above and beyond.
After hearing the problems that bus nuts in other parts of the country have finding people to work on their buses, I am really luck to now have two quality shops where I can take the bus.
I would almost bet that system has a orifice hidden some place that will need replacing
Quote from: luvrbus on June 21, 2018, 07:18:21 PM
I would almost bet that system has a orifice hidden some place that will need replacing
Orifice? Are you generically describing a part or is there actually a part in the system called that? The tech working on the bus has the GM manual and years of experience, so I'm hoping that it's not so hidden he is unable to find it.
That system uses an expansion valve to control the flow of refrigerant. The orifice type system didn't get used on the GM's. They were used in the cars in the late 70's onward, but GM didn't update the system on the coaches. Probably because sales didn't justify the expense of the change.
That is good to know the 5 buck orifice tube can cause a lot of head aches and so can a expansion valve
Here's one you can use, at least, in cars for better performance.
http://www.acsource.com/smartvov-highperformanceorificetubes.aspx (http://www.acsource.com/smartvov-highperformanceorificetubes.aspx)
Those tubes in the cars would plug up when the compressor started going bad and shedding aluminum and teflon debris. People didn't replace them after changing out compressor and couldn't get sufficient cooling because it was partially of fully plugged. That fine screen won't pass small particles
The system held vacuum overnight. Seems like we're finally heading in the right direction.
Quote from: chessie4905 on June 22, 2018, 05:57:42 AMHere's one you can use, at least, in cars for better performance.
http://www.acsource.com/smartvov-highperformanceorificetubes.aspx (http://www.acsource.com/smartvov-highperformanceorificetubes.aspx)
Those tubes in the cars would plug up when the compressor started going bad and shedding aluminum and teflon debris. People didn't replace them after changing out compressor and couldn't get sufficient cooling because it was partially of fully plugged. That fine screen won't pass small particles
I don't know about 4108 buses, but this sounds just like what I need on my 16-year-old TDI. Unfortunately, my VW guy tells me that it will run me over $1000 in labor alone to pull the dash and get into the A/C system. :-[
Quote from: chessie4905 on June 22, 2018, 05:57:42 AM
Here's one you can use, at least, in cars for better performance.
http://www.acsource.com/smartvov-highperformanceorificetubes.aspx (http://www.acsource.com/smartvov-highperformanceorificetubes.aspx)
Those tubes in the cars would plug up when the compressor started going bad and shedding aluminum and teflon debris. People didn't replace them after changing out compressor and couldn't get sufficient cooling because it was partially of fully plugged. That fine screen won't pass small particles
Huh...a good shop shows you that, makes you feel all warm and fuzzy, that they know what they're doing...
My 2003TDI never needed any ac service or freon added. 254,000 mi. Only car I've had that didn't need some kind of AC work.
COMPLETION UPDATE:
Just picked up the bus and drove 40 minutes to get it home. Today's not particularly warm outside, but the a/c did make consistent cold air all the way home. The tech first ran a nitrogen pressure test with leak check yesterday. That tested fine so he proceeded to evacuate the system and left the vacuum all night. It held steady and didn't lose any vacuum. This morning he refilled with 25 pounds of refrigerant. The service writer was surprised at how much refrigerant the bus swallowed, until he peaked at the size of the evaporator and condensing coils. Big enough to cool a small office building.
The invoice shows that they used R438A25 R22 as the refrigerant, which seems to mean that they used one of the modern replacements for the r22. When I got home I did some research online, and I believe this refrigerant is commonly referred to as M099. The write ups seem to indicate that it's a direct replacement for the r22 with compatibility with the mineral oil used in the existing system. The only thing that the write up said was usually needed was installation of new seals.
Since we installed a new compressor (with new seals) I guess that this was the perfect time to make the switch. At least if there is a problem down the road I'll be able to get things repaired without having to swap refrigerants later on.
Surprise, surprise...the R438A costs just as much as the old r22. Go figure.
LOL cost a bunch of money to leave Chlorine out of the Freon one would guess
https://www.amazon.com/CHEMOURS-R-438AX25-Refrigerant-Disposable-Cylinder/dp/B00HGIRURA/ref=sr_1_2?ie=UTF8&qid=1529696426&sr=8-2&keywords=r438a+refrigerant (https://www.amazon.com/CHEMOURS-R-438AX25-Refrigerant-Disposable-Cylinder/dp/B00HGIRURA/ref=sr_1_2?ie=UTF8&qid=1529696426&sr=8-2&keywords=r438a+refrigerant)
Brief update on the OTR a/c after the trip to Wyoming and back...
There were two areas of concern regarding how the unit would perform after the update:
The first was the slightly larger clutch pulley at 6" instead of the original 5.5" diameter. The new compressor with the larger pulley worked just fine. It might have taken a couple of minutes longer for the system to reach full cooling capacity, but I really couldn't say so definitively.
The other concern was the replacement refrigerant, M099. Happy to report that the new refrigerant seems to work just fine.
After about twenty minutes on the road, the entire coach was easily kept at a comfortable 72 degrees in spite of outside temps in the upper nineties with full sun. If I had the temp control knob on the dash set to max cool, it got meat-locker cold in there, especially at the start of the day when the outside temps were cooler. The driver's area was slightly warmer due to the sun beaming through the windshield, but nothing the driver's fan couldn't cope with.
I'm really glad that when I struggled to get the heating circulation (booster) pump replaced/rebuilt I also had the water modulating valve replaced with NOS from Luke. The water modulating valve is what allows the temp to be moderated by running the heat as necessary to keep the coach at the desired temp. The a/c compressor runs constantly when on, so the only way to moderate the temp is through this system.
I know that now everyone has or wants the OTR HVAC system, but if there is anyone deciding to keep or scrap the system I'd encourage you to keep it if the system is salvageable.
You'll feel that way till the next time it goes down and costs $$$. Glad it is working fine.