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Cold dropping out during RPM acceleration

electrodad on Fri July 17, 2015 7:35 PM User is offline

Year: 2006
Make: Chevy
Model: Malibu
Engine Size: 2.2 L
Refrigerant Type: 134a
Ambient Temp: 82
Pressure Low: 60
Pressure High: 150
Country of Origin: United States

My 06 Malibu recently has stopped cooling like it originally has in the past. We had it checked for leaks @ the local chevy dealership and they cold not find any. I have checked the pressures with a gauge set and during curb idle (in park) we get approx 20 degrees colder from the vents. When the RPMs are raised to approx 2000 the temp rises and no cold air from vents. The pressures goes from 45/175 to 60/150 ....when we go back to curb idle the pressure slowly returns to the 45/175 and the vents blow cold approx 20 degrees colder than ambient. Any ideas? I don't want to waste time and money repairing the wrong thing. Thanks

TRB on Fri July 17, 2015 8:04 PM User is offlineView users profile

Sounds like you could be having a control vale issue. If the system is correctly charged with refrigerant.


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GM Tech on Fri July 17, 2015 9:39 PM User is offline

As long as you are positive the system is charged to factory spec, then, yes, compressor is de-stroking too soon- I'd try a new control valve- mounts in rear of compressor.

Checked for leaks??? Did the recovered refrigerant weight indicate a loss of refrigerant? I don't check for leaks when I pull out a full charge. And if it is less than full- I know there is a leak and have to do a serious leak checking.

I would have pulled charge, weighed it, then evacuated and recharged to factory spec and then see if system can cool at 2000 rpm, before I replace anything. Did your mechanic at least do that- or did he just check for leaks.

Loss of refrigerant is the number one cause of mobile a/c failures-- I'd play the odds....

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: Sat July 18, 2015 at 8:53 AM by GM Tech

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