Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

A Bus Project

Joe Camper on Thu August 25, 2011 8:27 PM User is offline

Year: 1993
Make: Prevost
Model: XL
Engine Size: 8V92TA
Refrigerant Type: 134A
Ambient Temp: 85
Pressure Low: 23
Pressure High: 200

New here thanks for having me. In an attempt to simplify Im cuting and pasting something I started at another forum first.

Thanks in advance for any assistance.

If it were easy everyone would have it.

Edited: Thu August 25, 2011 at 8:30 PM by Joe Camper

TRB on Thu August 25, 2011 11:47 PM User is offlineView users profile

My first question would be. How do you know the switch failed and was the reason for the compressor locking up? I don't; work on these types of systems much. But would wonder if it failed do to lack of lubrication.


When considering your next auto A/C purchase, please consider the site that supports you:

mk378 on Fri August 26, 2011 9:02 AM User is offline

There was only 4 oz of oil in a system that holds 13 lbs of refrigerant? Seems clear to me that it seized due to lack of oil.

Multiple evaporator systems are tricky to keep the oil flowing back to the compressor instead of getting trapped in one of the evaporators or lines. Some other people here have experience setting up oil separators to keep the oil from leaving the engine bay in the first place. It traps the oil in the discharge line from the compressor and immediately returns it to the suction side.

HECAT on Fri August 26, 2011 9:14 AM User is offline

A large 3 evap system using a 13 lb refrigerant charge; and only 4 oz of oil was added after flushing? This would be why the compressor only lasted 5 or 6 hrs. The pressure switches usually do not detect enough pressure change to protect the compressor from burning up from lack of lubrication. Drain the shipping oil from the new compressor, flush the entire system again, and put in the full factory oil charge. Do not rely on the compressor to have the correct amount of oil in it for your application. HTH


HECAT: You support the Forum when you consider for your a/c parts.


bohica2xo on Fri August 26, 2011 6:55 PM User is offline

There is not enough information in that thread to make anything more than an educated guess.

When you state that the conversion company uses a "much larger compressor" - we need to know which compressor.

Most pusher bus applications I come in contact with are running a TM31HD compressor like THIS.

If your "larger compressor" looks like that, it has a sightglass on the sump. Base charge is 500ml of PAG100, so a HALF LITRE in the sump. On a flushed system, this may mean much more oil than that to get to "full". We use an oil injector pump more common to commercial refrigeration to add oil after running for a few minutes. Charge, run 10 minutes at idle. Check oil. Add. Run again. Until the oil is someplace in the sightglass after running. The road test a few miles, and re-check. Adjust as necessary.

4 ounces? Ha! Not even a couple of strokes on This baby.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.