Automotive Air Conditioning Information Forum (Archives)

slls on Sat July 17, 2010 9:56 AM

Year: 1999
Make: GMC
Model: sonoma
Engine Size: 2.2
Refrigerant Type: 134a
Ambient Temp: 80 F
Pressure Low: na
Pressure High: na
Country of Origin: United States

Bought Sonoma new, 59K miles. System never serviced, sets in garage most of winter. AC used sparingly in summer.
When I have used it last couple of years it will blow cold then go warm then back to cold. Today I decided to do a temp check.

In shade, both doors open, selector max, fan on #4 1600 rpm, went to 51F then too 60F like when driving then back to 51F.
It stayed 51F and did not cycle to 60K again. On #2 fan 1600 rpm 40F and steady.

My question is why does it do the cold to warm to cold cycle one time, does it need service.

bohica2xo on Sat July 17, 2010 11:25 AM

You have a V7 compressor, and it is undercharged.

Running it undercharged causes it to starve for oil. GM tech will be along shortly to explain this in depth.

B.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

slls on Sat July 17, 2010 8:31 PM

Thanks for the reply, I will get it charged.