AC Compressor Leaking

[dreamchasers]

After rebuilding my bus air condenser fan system on my Country Coach, I decided to pressure check the system before recharging with R-12. I applied 250 PSI of nitrogen to pressure check the system and had no leaks on the condenser that I rebuilt, but the compressor leaks at the seems. A quick call to Omega Systems in Dallas resulted in a great conversation with JD Huff, their AC Sales Manager. He stated that if these large AC compressor overheat, leaks can occur at the seams such as mine does. He suggested that individuals have had success with installing a refrigeration system sealant, but I chose not to take that route. Mine was low on oil, thus the overheating. Mine has a convenient sight glass on the compressor's side to see the level. I discovered the low oil level during the bus air service.

I have never seen an AC compressor leaking at the seams.

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If you have a system that leaks down over a long period of time, here is a place to check.

This applies of Country Coach owners with the Country Coach bus air system.

Hector

[truk4u]

Hector,

I just changed out my dash a/c compressor and it was also leaking out the back of the case at the shaft seal. I put on a new one and I'm going to rebuild the other for a spare. Mine also was low on oil, I drained about 3 0z and it should have had 14oz.

You would normally expect a hose or fitting leak, but the compressors themselves are probably the culprit on many a/c jobs.

[dreamchasers]

This post is of special interest for Country Coach Owners with the Country Coach installed bus air.

My existing AC compressor was tired after many years of running with only one of two electric condenser fans working and operating at excessive discharge temperatures. The AC compressor leaking case is result of high temperatures stressing the AC compressor case (per Omega). Now the cooled suction (from the evaporators) refrigerate temperature is approx 66 degrees and the discharge temperature is 202 degrees. These temperatures were taken at the compressor suction and discharge manifolds.

I replaced the OTR AC compressor with a new TM-31 ordered from Omega Systems ($1,126.00). The compressor came with PAG oil for R-134A, so I drained the oil and replaced with mineral oil compatible with refrigeration systems. After replacement of the compressor, I pressure checked the system for five days @250 PSI, no leaks. Then evacuated the system and recharged with R-12. My results are outstanding! I took a few pictures of the particulars so other Country Coach owners can see my statistics. I also replaced both electric condenser cooling fans (One was not operating when I refurbished the system.

My bus air is working great!


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I charged the system on a cool day, outside temps 60 - 70 degrees. My suction pressure ended at 18 psi, with a discharge pressure of 140 PSI. Since I was using R-12 refrigeration, I charged the system until the return refrigeration from the condenser (Viewed at the sight glass on top of the dryer) was 'bubble free' and 'liquid clear'.

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The discharge temperature at the galley evaporator was a brisk 33 degrees. I am sure I will appreciate that temperature this summer.

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This is a shot of the new condenser fans installed. I did remove the condenser assembly to replace the fans. This is a shot of the condenser assembly, with new fans mounted under the bus.

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The new AC compressor mounted. I like it!

[jack14r]

That looks great,what is the temperature differential with r12,I bet it is much greater than we see with r134a.

[dreamchasers]

Great question Jack. But unfortunately, I do not know.

Any AC experts out there?

Hector

[jack14r]

Hector,measure the return air and the discharge air to get the difference,I bet it will be more than 21 degrees with R12.

[Jon Wehrenberg]

Cynic that I am, why would a new compressor of the same design be expected to perform any differently than the old one that Tom and Hecotr and others have had problems with?

That is a design fault.

[truk4u]

Jon,

My issues were with the dash air compressor and not the CC OTR compressor and was only 240.00.

Nice job Hector, how much freon did the OTR hold? The dash air was only 6 - 7 lbs. My dash air compressor also came with PAG oil and I changed it to Mineral. Now I read where PAG is compatible with Mineral, but the A/C compressor manufacturer insists that you change to Mineral.

[rahangman]

Good for you Hector. Your endeavor seems a bit much for what I might want to tackle myself and I need it. My air has not worked since I got the bus. I did have it checked (vacuumed and leak checked and it proved to be good , so , I may want to put together a program such as yours to see what I can do. Thanks for your work and sharing the info ... all of us CC owners owe you. At least us with the older buses.