over road air

[JohnEd]

Bob B,

Firstly, I was told that trying to converting a R12 unit to R22 was not possible.  Obviously that AC Systems engineer was wrong.   Can you give me more info on that?

I am curious why you didn't convert them to 134?  I have heard that 134 was weaker than R12 if you just refilled a R12 system but it did work.  Obviously it does as I have 2 systems that are doing OK.  My Lex was built for 134 and it is the most spectacular performer I have been exposed to.  Guess it should be though.

TomC,

I think I know what a "scroll type" compressor is.  Like the blower on the GM 2 cyc....right?  If there are no pistons and the resultant recip mass you would have to be more efficient.  Is that a newly introduced tech to auto engineering AC?  I could wander downtown and ask stupid questions( getting to be my trade mark ) but I hope you can inform me as well.  It wasn't clear to me if Sanden made the scroll you mentioned.  Do you have a make auto that has that tech in it?  If you have time....

Thanks,
John

[larryh]

Now topic is being hijacked I'm not trying to change my system to a different freon I removed orig compressor and condenser, evaporated and all controls. My heater/a/c unit in front of buffalo 4905 has a unit for the air there and all the fittings/outlets still there I want to make a mount and drive it off the original drive shaft that drove the big York compressor and run lines to front unit.

Larry Higuera

[JohnEd]

Larry,

My comments about "freon type" are not a hijack.   Everything today is 134.  134 uses a specific type of oil.  134 has been around for awhile and there are lots of used components for you to choose from.  The "old" gm compressor wasn't designed for 134 and it has other oil in it from when it was run with R12 or 22 but you can load it with 134 and it will work.  I don't know what the trade offs are but there must be some somewhere.  Things I have heard over the years are that the oils are not compatible with each other or with the two freons and that 134 will permeate R12 spec hose.  I am not sure of that but I would be if I were converting a system.  My advice to you was to make 134 part of your search and selection criteria for your new compressor and condenser.  Further along those lines is the fact that the 134 systems use a "different" fitting for charging the system so you can spot one of these systems from across the room(shop) and also not get ripped off if you know what you are looking for.  Maybe you plan to stick with the original equipment and use R12 but you should know that the Fed has made it illegal in cars as a "new" system and with the tax it costs something like $100 per pound.  134 is only $4 or 5 dollars per pound or so...... Add to that your need for a special licence to even purchase R12 and you can see why it has down sides and I would think to bring it up.  You did say "i am not an AC guy" right?  Neither am I.  Remember what the tortoise said to the Hare....I might be slow but I am ahead of you.         

TomC said you should try for a "scroll" type compressor due to its efficiency and power and that also makes perfect sense to me.  I think that is info you can use as well.  I don't think that compressor design was part of you original question but you are better informed now than you were when you asked it.  I sure am and for that i thank you.

About those belts:  You didn't ask about them but if you look thru your replies all of the compressors are belt driven.  Big reasons for that and when you select your pulley sizes you will get into one of them.  All engines don't turn at the same rpm and we adjust the compressor speed by selecting pulleys.  The same goes for belt width.....the old GM style needs a wider belt(multiples) to accommodate the torque needs of that unit and the efficient newer generation gets by with the less power robbing smaller V belt or "flat" belt.  A flat belt drive may be part of your search criteria now that I think of it.  Even if you could direct drive your new compressor from your "drive shaft" I thing that would be a big mistake...most likely.  Not to mention a serious challenge.

There is an old saying: "if a man asks you what time it is....don't tell him how to build a watch".  Problem is that Rookies don't always have the knowledge to properly ask for the info they need.  I am certainly in that group and if all I got was the concise answer to my question I would be the lesser informed man for it.  On the other hand, I can easily imagine that an informed individual might answer a lot of my questions with a curt "insufficient data to respond".  I hope that never happens to me.  If you chastise people for not being sufficiently psychic to fully understand what the heck it is that that you want I can easily understand how you would get answers like that.

The post that gave you pics about adding a center coach evap unit for cooling the center/rear of the coach while underway really helped me.  I had prior info that that wouldn't work and there it was doing all I would have hoped for.  I am sure glad that guy didn't limit his response to you having a cooling unit in the front of your bus.  When you install your system you might not want to install a center unit but you might consider running freon lines up to the dinette bench(or wherever) for the future and if you never use them no problem.  People keep telling me that planning is critical and planning with flexibility is really smart. What are they telling you? You didn't ask about that but I would be disappointed, if only for my sake, if you chastised that guy for interfering with ...with....with what....your ignorance??  He sure stepped all over my ignorance....thank God he was inclined.  I hope you see the humor in this as I intend that that be an element.

If you only want specific answers to your questions and endure no risk of the thread wandering, you need to "NOT" say things like "Any hints or pics would be appreciated" or "I am not an AC man and I need to learn".  Those kind of comments "REALLY open the door".  So Larry, don't be too hard on us.  We are all muddling through this trying to do the best we can and for some, it has been my experience, that is "outstanding" beyond my wildest imagination.  There will be lots of times when you will have to read through our(my) responses carefully for the info you wanted.  And for our(mine) lack of forsight we(I) do apologize.

Larry, please know that i was smiling through all of this and I am not ticked or seriously disappointed in anything you said as I always consider the source.  I intend this to be constructive and humerus.  You might want to tell all that responded "thanks" for all the info they took the time to provide you that you didn't specifically request and that might be loosly considered "hijacking".  I am sure grateful to them and I know many others have benefited as well. 

Don't forget now....smiling and chuckling with warmth in my heart.  This is a flat medium.


John

[buddydawg]

I intend this to be constructive and humerus

In order for bones to do anything constructive, you must have at least two of them....

[JohnEd]

Buddy,

I wondered how long it would take....and the answer is 17 minutes.   Good work.

I couldn't resist ....that may be a problem.

Thanks,

John

[kyle4501]

You can get the 'old' GM compressor with out any oil in it & is quite happy with whatever oil the refrigerant requires you to use.

134A is not my first choice for refrigerants due to its trait of mixing with water to create acid (- no forgiveness if the dryer fails ) & since it is a smaller molecule, it will escape the system faster. R22 can work, it just operates at a higher pressure than R12 or 134A for a given temperature. So the system pressure set points have to be adjusted accordingly.

To keep it all simple, pick a refrigerant that is a 'drop in' replacement for what was in the old system & get a compressor that is set up to work with that.
You should still flush the system & replace the receiver & dryer as part of the 'up grade'.

[JohnEd]

Kyle,

I am right there with you Buddy.  The first thing that popped into my mind was the old GM.  The AC people turned me around, not cause the GM was defective but because there were units that were as reliable and more efficient and a couple that were bigger.  But I take no issue with anything you said and that's not cause I know anything about AC.

I think the change over kits do not mention changing the dryer.  That seems a real pity given what you told me about 134 having an affinity for water.  I think water would take out the entire system....every component.  Good info.

Is there an alternative to 134 that is common in automotive?  I didn't think 22 was an option cause it takes too much pressure to liquefy.  I don't think I would like to do that but it is nice to know in case I get my back to the wall somehow.

Kwi Chang Kane said "I have never hoped to have all the answers....only to understand all the questions."  Smart guy, that.  I loved that show.

Thanks again for your post,

John

[kyle4501]

I guess it may depend on who you talk to . . . . I can get an old GM A6 with clutch for ~$100 out the door - it is a rebuilt unit tho . . . . I haven't found anything else close that $ that was worth taking home 

But, in my limited experience, I've had as good or better success with rebuilt vs new. 

There are other refrigerants available, but DuPont stands to lose a huge amount of revenue if some other refrigerant becomes common place . . . .

Interesting R12 was OK for years until the royalty was soon to expire - which means DuPont would no longer collect $$ from any & all R12 sold.

Thank goodness DuPont had a replacement in 134A that could "safely" replace R12.   

Nope, nothing under the table there . . . .


Will be interesting to see what happens now that some European countries are moving to embrace CO2 as the main refrigerant due to the hazards posed by 134A . . . .

[JohnEd]

Kyle,

Thank you.  All veru interesting.

John

[Nick Badame Refrig/ACC]

Hi John Ed,

I have R-22 in my OTR system and it's a 134-A system. 2 years now but, that was when R-22 was cheap.

44 deg's out the vents and I was lucky to get 58 deg's with 134-A. Last week going to the Delaware Rally

it was in the 90's and still had to shut the OTR off to keep from freezing everybody out of the bus.

R-22 today my cost for a 30lb bottle is about $216.00

134-A today my cost for a 30lb bottle is about $80.00

It would make sence if the time comes that I may need to add refrigerant that I use R-134-A...  $$

Good Luck
Nick-

[NJT5047]

Nick and everyone, what's the compatibility of compressor lubricants used in R-12, 22 and 134? 
Aren't they different? 
I suppose that since larryh is starting with only an evaporator, that ain't going to be an issue.
But it would if someone used the OEM AC lines with residual lube laying all about?
JR

[larryh]

OK guys don't want to approach this wrong but I hate belts wether it is a chasity belt of a compressor belt what I want to do is use my shaft drive the turned the original compressor. and make a flange to hold my shaft to the compressor to turn a replacement compressor and to use the present clutch to turn compressor on and off I guess nobody else has done this so I will experiment when I get back to AZ for the winter.
Thanks for all the input.

Larry Higuera

PS: next time I will be more explicit in my question.

[kyle4501]

Interesting take on that Larry. I'd be very interested in what you come up with.

[JohnEd]

Larry,

I am also interested.  Do you know what the RPM for the old compressor is and what the new one needs?  That was one of my points.  If I could direct drive anything I would prefer that to a belt anyday.....for sure.  Rpm matching is the problem as I see it.

We sure as heck have gotten our money's worth out of your thread.  Thanks!

John

[JohnEd]

Nick,

I would have used R22 long ago if I had known that it would work.  Does it take the same oil as R12 used to?  Curious only.  I guess they have R22 oil in a can like they have for all the other auto stuff.

If the system is designed for R134 doesn't it do a better job?  58 degrees is abysmal and a non starter in my opinion.  I haven't ever measured my 134 system but I can freeze anybody out.  When I converted the Thunderbird to 134 I thought the performance fell off some but it still worked ok.  It might have not cut it in Palm Springs at 120.

I want to change out my York.  Talk about vintage.  I want to use a 134 compressor but I don't know which one or what year and make it could be taken from.  I think I will get better response if I start a new thread.

Thanks,

John