Automotive Air Conditioning Information Forum (Archives)

Jack32 on Wed June 08, 2011 2:53 PM

Year: 1998
Make: Chevrolet
Model: S10
Engine Size: 4.3
Refrigerant Type: R134
Ambient Temp: 92
Pressure Low: 40
Pressure High: 250
Country of Origin: United States

Hello,


Last weekend I replaced the original leaking compressor with a rebuilt AC-Delco. I replaced the accumulator/receiver/drier with the OEM from delaer. The total oil capacity for this ac system is 8 oz PAG150. I added 3 oz to compressor, 2 oz to accumulator and 1 oz to the hose. I turned the compressor clutch approx 40 times to spread the oil. Pulled vacum for 1 hour. And observer the gauge for gauges for 30 minutes and no were apparent.

I added three 12 oz cans to the system (System spec is 30 oz of 134). All seems well except the temp at teh air vent is only 50 deg F
I can seem to get the temp below this. Charging he system over the past 3 years I was always able to get the tempts down to 38-42 degrees. do you guys have an idea? I shouls add that it is very hot today and teh truck is sitting in the afternoon sun when I was checking pressures and temps.

thanks guys

JJM on Thu June 09, 2011 12:25 AM

Could also be the system is slightly overcharged. Granted, you probably lost a bit switching cans, but 6 oz might be an over estimate.

Recover a little refrigerant in 2 oz increments and see if performance improves. If so, the system was overcharged (though the pressures don't seem to confirm this).

Joe

TRB on Thu June 09, 2011 12:30 AM

Could be too much oil also . Depending if the system was flushed or not.

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Jack32 on Thu June 09, 2011 10:10 AM

Thanks for your suggestions. I thought it migh be overcharged as well. During the drive into work this working I took temp readings at the vent with the AC set to MAX, blower on highest setting and driving at highway speed. The readings were a very chilly 36-38 degrees. Now I'm thinking just leave well enough alone. The truck has 200k miles and I only expect to keep it another 2 or 3 years.



As far as too much oil, I have been adding about 1-2 oz a year for the past 3 years while I was replacing refrigerant. The system was not flushed prior to installing the new compressor and drier. I just assumed that there was still 1 oz in the evaporator and 1 oz in the condenser

mk378 on Thu June 09, 2011 2:46 PM

Too much oil is likely. Most new compressors come with plenty of oil in them for the "benefit" of the guy who's going to just slap it on without doing anything else. Also the typical slow leak doesn't lose much oil, only gas unless it's in a low spot, so adding oil when topping up a leaky system isn't always good.

If it's mostly an issue of performance at idle, a new fan clutch might help.

Jack32 on Wed June 15, 2011 12:04 PM

I just realized that I added 2 oz of oil to the exit side of the accumulator NOT the inlet side. Could this affect performance?

JJM on Wed June 15, 2011 9:19 PM

Not at all. Doesn't make a difference where you put the oil, it's all gonna migrate throughout the system anyway.

Joe