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Compressor not engaging

jdub on Fri July 02, 2010 9:51 AM User is offline

Year: 07
Make: Saturn
Model: Vue
Country of Origin: United States

Trying to figure out if my loss of A/C in the Vue is something I can tackle or not... The A/C quit cooling suddenly after working very efficiently up until that day.

The compressor is not engaging any more. I can't find any visual signs of hose or fitting break and the fuses are good. I want to check low-side pressure to see if there is any pressure at all or if it has dropped below the sensor cut off limit. Can someone tell me what the low pressure cut off sensor is set to and also what is "normal" pressures for an engine not running and at idle on an 85 degree day?

If the pressure is correct I will assume there is no leak and try to jump the compressor clutch by wiring direct to see if it comes on. If it does, then I will try to find out if it is just a bad relay or an actual mechanical problem with the clutch.

Is there anything else I can check before taking it to the mechanic? I don't want to just randomly dump some refrigerant in and hope something good comes of it, but I also don't want to take it to the shop if I just need to pull a bad relay out of the electrical block and plug a new one in. I do have a borrowed set of gauges and vacuum pump so if the pressure is all out I think I am comfortable finding a hose leak with dye and replacing the bad hose or connection, desiccant can, and pulling vac to refill, but if it is a slow leak or bad component I think I will take it to the shop as I don't have any means of capturing the remaining refrigerant and am not an expert on system diagnostics.

Any suggestions or thoughts would be great.

Edited: Fri July 02, 2010 at 10:17 AM by jdub

bohica2xo on Fri July 02, 2010 2:59 PM User is offline

Static pressure should be what ever is listed in the P/T chart for your system temperature. If the underhood temp is over 100f, expect static pressures above 100 psi.

Two different A/C systems in the '07 Vue. Is yours a GM 4 banger, or the Honda V6?

B.

-------------------------
"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.

jdub on Fri July 02, 2010 3:34 PM User is offline

Thanks for responding Bohica. It is the teeny weeny GM 4 banger hybrid. (wifes ride)....no, really! =*)

UPDATE - ok, so I did a visual check and the compressor IS engaging and spinning. I just couldn't hear the "clack" over the engine running.

I am at 93psi both sides with engine off and cold. Ambient is 83 in the sun. The pressure chart says it should be 95psi at 85 ambient so I am guessing all is good. I crawled all under and over and can't find any leaks. The sticker says the R134a is dyed already and I see nothing.

At high Idle (1000rpm) and full a/c the low side drops to 85psi and the high side stays at 93psi. I also ran it for a minute or so at 1500rpm and the high side never went up any, although the low side did drop a little more....about 83psi.

Air temp at vents never changes at all.....If anything it gets hotter when revved.

With the compressor running and no apparent leaks, I am at a loss here. Any ideas of what to check next?

Damn.....It's supposed to go back into the upper 90's again this weekend.

bohica2xo on Fri July 02, 2010 3:59 PM User is offline

Well, it looks like your variable scroll is at minimum stroke - or just dead.

While the compressor might be repairable, flat rate hours are such that mechanics have become parts changers. Expect most repair shops to tell you the compressor needs to be replaced.

I would call the nearest Chevy dealer and get a quote on a compressor replacement. Yes, the dealer. Saturn service has been handed off to the Chevy dealer, and they realized that the brand loyalty of the Saturn line was much better than the rest of GM. The local dealer has been bending over backwards for Saturn owners here. They just did the service on my wifes's 07 Vue for free (40k miles), and replaced the cabin filter & wiper blades N/C. Washed it too.

They relocated all of the special tools & trained mechanics to certain dealerships. They are trying hard to retain that business.

B.

-------------------------
"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.

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