Year: 2002
Make: GMC
Model: Sierra
Engine Size: 6.0L
Refrigerant Type: 134a
Ambient Temp: 106 F
Pressure Low: 51 psi
Pressure High: 295 psi
Country of Origin: United States
Hi,
I'm a licensed HVAC contractor, but new to automotive.
The above measurements were taken at a idle of 800 rpm.
Compressor, condenser, accumulator, metering device and a high side hose replaced.
Leak tested, flushed, 8 oz of PAG 46, evacuated to 400 microns for 2 hours.
Weighed in a charge of 18 oz
OEM charge calls for 29 oz.
Normal cruise speed rpm is 1800-1900. At this driving range I get a 45-47 degree F at the center supply register with 106 F outside. Compressor stays engaged at all times except for acceleration, which I think is normal.
I'm afraid to add more refrigerant, to bring system up to OEM specs, with the pressures and temps that I have now.
Does anyone in Arizona run a 'low' charge to compensate for the high ambient temps that we have?
Any ill effects on the compressor?
Without a full charge all the oil tends to pool up in the evaporator, which is bad for the compressor. Always use the specified charge amount.
High side getting too high is typically because of inadequate condenser cooling. On a full size truck with engine driven fan, the fan clutch can be worn out. Fan will still spin but not as fast as it ought to. Triple digit weather will stress any system though; being over 300 on the high side in such conditions isn't necessarily abnormal.
Edited: Thu August 15, 2013 at 10:15 PM by mk378
Thanks,
Temps have dropped to 100* F and I added the remainder of the ref into the system. It did not change the low or high side pressures, so I assume that the ref is being stored in the accumulator.
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