Re: [DML] A/C problem: compressor is not cycling

[Travis Graham <tgraham@xxxxxxxxxxx>]

I think this one's solved... for now, at least.  To recap, I had a  
concern that my A/C system pressures weren't quite right.  I also did  
not notice my compressor cycling.  I got several suggestions and  
several pointed to a possible low oil level in my A/C system.

Last weekend I ran the car with the A/C on for 20 minutes, them  
immediately reclaimed the R-12, removed the compressor, and drained  
the mineral oil.  I didn't get much old oil out at all - my system  
was apparently very low!  I then re-installed with new o-rings all  
around, added 7 oz of fresh mineral oil, vacuumed the system at 27 in- 
Hg for 1.5 hours, held that successfully for 1 hour, recharged with  
2.25 pounds of R-12, and now I'm getting these pressures:

ambient temp: 85 deg. F
rest pressure: 66 psi

@idle:
low side: 45.5 psi (was 42 psi)
high side: 160 psi (was 155 psi)

@2500 RPM
low side: 30 psi (was 28 psi)
high side: 235 psi (was 206 psi)

@3500 RPM
low side: 29 psi
high side: 250 psi

There were three variables since last time: 1) 0.25 additional pounds  
of R-12, 2) more oil in the system, and 3) much longer evacuation.   
The compressor still does not cycle when idling, but I understand  
that's not a problem in my scenario (hot and outside).  I don't know  
why the idle low side idle pressure was higher this time around, but  
the rest of it seems like a step in the right direction.  The output  
at the vents is colder, especially at idle.  Now I just have to find  
the leak (if it wasn't any of those o-rings on the compressor) and  
get that fixed.

A big thanks to David Teitelbaum, Tom Niemczewski, and Harold  
McElraft for their on and off-line advice.

Travis Graham







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