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


Does your compressor cycle at higher RPM? Those measurements at 2500 and 
3500, are those the numbers you see when the clutch cuts off? If yes then 
you don't need to touch the low pressure switch as it is right where it 
should be. It should switch the compressor off between 25 and 32 PSI. The 
problem is at idle... That might indicate a weak compressor which might be 
the result of running it without sufficient amount of oil. On the other hand 
you high RPM results are in the high range which might indicate poor cooling 
at the condenser. Are both cooling fans running at full speed? Make sure the 
fans are well secured on the shaft as sometimes happens that they spin on 
the shaft when the metal clip is lost. Is the condenser clean? Do you have 
both the front and rear radiator shrouds? Those number might also be a bit 
high when the car is not moving and there simply isn't enough air moving 
through the radiator.
One last question... at idle when you see 45 and 160 psi, is it a constant 
reading or do the needles bounce a lot or vibrate? If they do then you might 
have malfunctioning reed valves in the compressor. This might be due to 
running the compressor dry, crack in the valve or valve seat or simply 
contamination of the system... something might get stuck in the valve and 
keep it open.
I think we can move this conversation to direct emails as not to clutter the 
list. Email me directly or if you'd like you can send me your phone number. 
I can call you and help you over the phone.
I'm sure we can figure out what the problem is and get your A/C as cold as 
it should be :)

Good luck

Tom Niemczewski
vin 6149 (in Poland!)
Google earth: 52°25'17.30"N 21° 1'58.00"E

----- Original Message ----- 
From: "Travis Graham" <tgraham@xxxxxxxxxxx>
To: <dmcnews@xxxxxxxxxxxxxxx>
Sent: Monday, 28 August, 2006 10:37 PM
Subject: Re: [DML] A/C problem: compressor is not cycling

>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

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