my 78 MCI still has all the road AC system in place. PO told me when I purchased it that the system was low and he didn't ever run it. I have 2, 30lb bottles of freon 12 to charge it with but can't find any pressures in the manual. Do I go solely on level in sight glass up at condenser ?
Is it "low" or empty? If empty, you need to pressure check it before wasting the R12. Rarely is it practical to try to maintain coach AC unless it is only a couple of years old $$$$$. I won't even go into proper training and certification to handle refrigerant/ AC systems.
I believe it's low, I haven't turned it on yet. PO had run it and it wasn't getting very cool, bus came from northern Ca so he didn't need it he said. I'm in texas so different story.
1/2 of the glass on the lower glass at the receiver is normal you may need to adjust
It went somewhere... ???
Why wouldn't you suck it down and pressure test it...??
Are you sure the road air uses R12 and not R22?
What kind of system? Is it a sanyo automotive type compressor that you could find in a car, or maybe a trane multi piston type of compressor that you find in a coach?
Ken
If his 8 hasn't been changed over to R134 A they did use R12 or R500 mine did before I changed to 134
Conversions to 134a usually have lots and lots of stickers everywhere showing that fact..
Would have to check the whole R12 / R22 question with the make and model of the unit, all the buses i work on are typically R22.
As stated already regarding the sight glass, if nothings visible, vacuum it down to see if it holds pressure.
Does the A/C clutch "engage"?
If his is original he does have a 3 cylinder compressor and it does takes R 12 or 500 no R22 it is a 7 ton unit and when working you can hang meat in a MCI 8.It was disappointing to me when I changed over to 134 all the money spent and less cooling lol the stickers where made by a Mark A Lot felt pen
The previous owner of the MC9 I owned had put R-414 in the OTR system. Shortly after I bought it I took it to the folks at Thermo King. They advised the 414 was intended for stationary systems. They pulled a vacuum on it, replaced a faulty valve with one I ordered through Southern Refrigeration, and refilled the system with Freeze 12. It was still cooling well when I sold the bus a few years later. That said, the bus, having been converted new by Custom Coach, didn't have a million miles on it. If I was looking at a system with many more miles/hours on it, my decision to put $$ into it might have been different. Just my experience.
Put the gauges on it. If it's got ANY pressure on it, just freon it up. If all gone , I would look for a leak or leaks. On the quote "Rarely is it practical to try to maintain coach AC unless it is only a couple of years old $$$$$." That's nuts. Mine is 24 years old and after changing the rotten hoses after I bought my coach 4 or 5 years ago, still a cooling. If you get it working, nothing better than freezing folks out in 100 degree weather riding down the road.
I've found that the AC industry will do its most to scare people away from doing their own maintenance.. Go read the forums on HVAC, its comical!
The AC automotive certification is an open test book online!
You'd think these "pro's" were defusing IED's the way they speak (on HVAC forums)
I am curious where he found 60lbs of R12 at a price you can afford I sure hope he didn't get taken like me and paid for propane
Lots of those..
A few years back we were sold some R22A HC (Super Freeze).. was just propane..
Didn't work one bit! had to vacuum out the system and charge with the real stuff!
I heard the FBI calls customers (internet rumors) to obtain order information.. just search R22a and you're see the posts..
Now if we get sciencey, propane will work to a certain point but thats too boring to go into!
I've seen them take it out of old refrigerators before
That would be a old fridge they have used R134A for the last 20+ years
RV units (those roof ones) use R22 (saw a 2007 with them) - but those units are also pretty much throw away from what I can see..
We have a 2001 with R22 also (Thermoking) and our carrier is R22 also..
And after seeing this thread, I decided to start our unit today which has been sitting for a few weeks.. 120f inside.. cooling only down to 96.. hmmm.. and all my AC gear is 1200 miles away..
Newer roof tops use the R410 now 2007 was R22
Lucky for me a friend had the freon in his barn, has had it for years never had anything to put it in so let me have for a steal. My bus was factory shell that went straight to conversion only 192k miles on it. Compressor is a carrier. Gotta go out of town for the week but plan on putting the gauges on it and see if it has pressures then filling it up see if she gets cold. Thanks for all the help I'll keep y'all posted.
I keep saying to myself " just go ahead and charge up the over the road a/c with R 134, all the retro fit has already been done". But then I remember that I've been playing with a/c since I was 10 yrs old and remembering that I've won a few and lost a bunch. Sure , I've got all the a/c certs and licenses, but that never kept me from trying the impossible. I remember back in the early "60's wanting to be the only kid on the block with a/c. I tore up a couple of old refrigerators in the dump and tried to adapt them to a '54 Chevy. I nearly poisoned myself with the sulfur dioxide refrigerant they contained.
I'm kicking myself for even saying it. If I don't charge up the a/c on my MCI 9, how will I be able to find the leak and fix it? I've got the bus disease bad--real bad. jack
My friends at Arrow Stage Line use Nitrogen with a blend of Hydrogen and Helium with a detector to find leaks on their buses, the blend they buy from a welding shop it's easy to pickup a low pressure leak with blend also
Quote from: oltrunt on June 24, 2015, 07:28:35 PM
I keep saying to myself " just go ahead and charge up the over the road a/c with R 134, all the retro fit has already been done". But then I remember that I've been playing with a/c since I was 10 yrs old and remembering that I've won a few and lost a bunch.
Yeah Jack, I keep saying that to myself as My Freeze 12 in bus for over 4 years is probably getting low and thought about topping it off with 134 but they (Experts like yourself say) the oil is different between 12 and 134 are different and one won't carry the oil though system. Don't know as I pumped 134 in a 12 GM pickup years ago and it ran for years before I sold it. No problem.
Guy's A 50/50 mix of propane and butane will out cool R12 or R134 either and won't leak as bad as R134 ,plus this can be ordered for about five bucks a can and a can of it is eqiv to a can and a half of R134!!!A lot of the older BB owners use this stuff.
REALLY!!!!!!
You think adding explosive gasses to a system they were never intended for is a good idea?
You and those others are the reason I had buy a refrigerant identifier.
What's wrong with using the refrigerants they were designed for?
So you think R 134 is not an explosive gas??????????
Not as much as straight Propane (thats being sold as a refrigerant)
Found this article:
http://www.acr-news.com/fake-refrigerants-we-should-be-very-concerned (http://www.acr-news.com/fake-refrigerants-we-should-be-very-concerned)
So you think R 134 is not an explosive gas?
No, I don't.
When used as designed, I've never had any issues.
I missing something here 134A is not combustible is it ? I thought only the oil in all freons was the only thing that would cause combustion.
I know R134 will have combustion at very high temperatures above 1500 degrees if I remember but about anything will with the right temperature
Two things just for the record First,In certain countries propane/butane mix is an acceptable refrigerant , second,I have never personally used it my self,all tho I would if I was sure the leak wasn't in the engine compartment. Now if you had a 20lb system and had a catastrophic failure where it let it all go at the same time ,it would make a pretty nice little bang .I am not advocating using this stuff.But I do think that it is worth knowing about.
I have a fair amount of experience operating MC-8's and 9's in a desert environment. I got a kick out of you Clifford saying you could hang meat in an 8 with stock AC. Maybe at 65F but not at 100+. Even with a brand spanking new 8 or 9 you ain't going to get the cabin down much lower than about 20-25 deg. from ambiant at 100. And that's with R-12 or Freeze 12 and a 5F30 compressor, the R134A with an 05G compressor does not perform near as well. The condenser and evap coils must be kept squeeky clean and a few other tricks. Before I wasted that refrigerant I would pull a vac overnight, recharge with nitrogen and see what happens. Pay special attention to the crankshaft seal and around the dryer, as well as hoses and fittings. JMO
Boomer,mine was a conversion with hot spray foam and double pane in motion windows when it worked it worked well but it always leaked.Welch had it blowing at 58 degrees for a price ;D
It was never the same after Nation converted it over to 134A.I had the crankshaft seal installed 3 different times over the years it seem to always leak ;D
That is one of the problems encountered when you convert from R12 to R134. The R134 evidently is much thinner than R12.Since it is impossible to change all the seals ,hoses and other components, if there is a weak spot any where in the system,the R134 will find it .Remember the conversions they sold for cars ,basically a charge hose and three cans of R134?? This is about what you get with these conversions except on a larger scale .On a conversion that would really work ,you would need to change the compressor ,the receiver/dryer and any other components that can be changed.That is why in most cases when you are shopping for a conversion and ask about the road air ,the owner will tell you that he just runs the genset and the overheads.