OTR AC compressor change out/upgrade

[JohnEd]

Guys,

My S&S has a York compressor in it.  Actually it works OK but leaks down every year.  Currently it is hanging onto the dregs of R12 and all the R12 oil that I have put into it over the years.  My info is the the York was the least efficient compressor that was ever made and also one of the most durable.  Gotta go!  I fear that if I load the thing with 134 I will not get what I need.  Nicks posts seem to verify my suspicions.

Before I jump in....does anybody have any suggestions?  I think from what TomC said that i want a "scroll" compressor with a capacity of 3 ton.  Thing was the operative word there.  Knowing a model no. would let me shop for a rebuilt and if anybody knows a car make and year that I could scavenge, well,that would be great.  Generally, any info you think I might need.

Thanks a lot.  Now to google "scroll".

John

[TomC]

Scroll compressors are more expensive than piston types.  The Carrier A-6 which is the old GM 6 cylinder with wobble plate is one of the more durable and powerful compressors.  It has been made since the 60's and is a favorite of mini bus owners for not only its' output, but its' output at idle, then being able to spin as fast as 6000rpm.  Sanden makes smaller versions all the way up to 10 cylinders, and Sanden is the compressor we use on the Freightliner trucks.  Go look at the Carrier website at the various compressors available.  Good Luck, TomC

[kyle4501]

I can't imagine the compressor efficiency being enough to merit much effort in changing over to a different style compressor. Your leak needs to be located before changing out stuff.

If it were me, I'd keep what I had & just add in 'freeze12' or some other compatible refrigerant - I'd even replace the receiver/ dryer & hoses while I'm there (assuming the leak wasn't in the compressor).



If you are all set to change to 134, then I'd suggest :
Replace ALL things rubber in the system - seals, orings, hoses, fill valves, etc.
Flush out the evaporator & condenser to remove debris & oil.
Replace the receiver & dryer.
Reuse your existing compressor - IF -it still builds enough pressure.
REPLACE the pressure switches with the 134 compatible switch so it operates at the proper pressures.
Top it off every year to compensate for the higher leak rate of 134.

Keep in mind, this is my opinion & may not be worth what you paid for it.

[Hartley]

Also remember that an r134 takes much less than an r12 charge.

The other trick is the suction side pressures for r134 is less than r12
so the overall pressure is a bit less than in the older systems.

If your system says it takes 3 pounds of r12, Then start at maybe 2 lbs of r134 and see where the pressures are on at least a gauge on the suction side.

There are many differing opinions both from a technical point to a tried it
and it worked anyway point.

Many of the later "KITS" only contain a set of O-rings, Fittings and a supply
of Ester or PAG oil. ( Mystery?? ) If you system is very old it could need the newer hoses. Or NOT in some cases. Technically the MFR's want to sell you NEW hoses, connectors, Evaporator valve and compressor change out.

The "KIT" instructions on some of them say to drain the compressor oil and install the new oil. Then fill the system normally. Many don't say to change the O-rings or that major rework is needed. There are conflicting reports about that.

I have changed the compressor oil and refilled a couple of car systems with r134 and had good luck with them. The key there is to eliminate any leaks before you waste the time and money.

The other option is the Sanden compressors. I bought some off eBay for around $120 and they worked great with r134 (although listed at r12 units). I oil charged with Ester Oil and put them in service over 2 years ago and they still work today and haven't needed to be recharged.

Dave....

[luvrbus]

John, Denso makes good compressors also don't limit your search for one brand

[JohnEd]

Guys,

Thank you all very much.  I will post some more when I get rubber on the road.  One of the things I had in mind was adding a cooling unit to the back so I guess I will trash the entire sys.  One thing I am hearing is that I should go with the old R12 system but charge it with "freeze 12".  I think Nick said he had great performance with that stuff but it costs.

My other complication is that mine is V belt driven off the crank and the newer systems us the multi-V flat belt.  I think I can get around that.

Later and thanks again...really,

John

[Nick Badame Refrig/ACC]

Hi John,

This is the company that I use. They are very helpful, and Fast!

http://www.polarbearinc.com/PBPC/homepage/Product.html

Good Luck
Nick-