Automotive Air Conditioning Information Forum (Archives)

chrisg44 on Wed July 17, 2013 7:35 PM

Year: 2002
Make: cheverolet
Model: impala
Engine Size: 3.4
Refrigerant Type: r134a
Ambient Temp: 85
Pressure Low: 35

I have a 2002 impala that has been blowing out hot air. Noticed compressor clicking every couple of seconds, and online forums suggested low refrigerant. I bought a gauge and coolant hoping it was low on refrigerant. Hooked up the gauge and while car was running the gauge was moving from 35-45 psi with the compressor clicking on and off every 1 second, so i didn't even open the 134a as it seems the pressure is proper, right in the green range on gauge. After a few minutes cycling stops and pressure was holding at 35psi. Then after a few minutes, the compressor starts clicking every second again.

Also noticed that passenger side fan in front of engine is normally running when ac is on, but driver side fan does not run until clicking of compressor stops, and then fan stops and clicking starts again. just really hoping i can get this diagnosed so I can fix as it is super hot and driving this car is difficult in 95 degree weather.

Refrigerant has never been added to this vehicle.

GM Tech on Wed July 17, 2013 7:42 PM

You have a variable stroke compressor- it avoids freeze-up by destroking- NOT cycling off--- like a CCOT system- If your compressor is cycling- you have high head pressure cut-outs occuring- or a very special intermittent circuit. What is your high side pressure- sounds like you don't know because you used a walmart gage only on low side--you either have an air flow problem (does it do this while driving 60 mph?) or a serious internal restriction-- high side readings are mandatory.....but rest assured, you are not low on refrigerant.

Also- does clutch (front of compressor) turn while it is engaged? I've seen seized pumps act like what you are describing...clutch engages- slips, grabs pulls engine rpm down low enough to enact "stall saver" algorithm- then releases clutch, then repeats this routine indefinitely while at idle...

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Edited: Wed July 17, 2013 at 7:54 PM by GM Tech