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Low side 40psi and compressor won't kick in?

atikovi on Thu November 22, 2012 4:51 PM User is offline

Year: 1999
Make: Saturn
Model: SC2
Engine Size: 1.9
Refrigerant Type: 134
Ambient Temp: 55
Pressure Low: 40
Pressure High: 40
Country of Origin: United States

This is 1999 Saturn SC2. The A/C was working fine the beginning of the year, then during the summer it would work fine one day and nothing the next. Now, nothing, and I want to take it to Florida soon to sell so it has to work to get a good price. I put the gauges on and they are at 40 psi on both. Shouldn't the compressor kick in as long as the low side is above 30? I hot wired the compressor and the low side gauge barely moved, maybe dropped 2-3 psi. Nothing noticeable on the high side. Is this most likely a failed compressor? Or is it low on freon?

bohica2xo on Fri November 23, 2012 12:37 PM User is offline

It is basically empty at that pressure.

Running the compressor like that means it has no oil return. Get a full charge in it, and let the system safety devices do their job.


"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.

NickD on Sun November 25, 2012 5:25 AM User is offline

Of course Freon is a DuPont trademark for R-12. 40 psi is close, but not close enough, should be over 45 psi, but won't get much cooling if it does kick in. If you do properly charge it to specifications, can only guess how long it will work. With low refrigerant like what you have, you have a leak. Depending on the degree of that leak, could work for a couple of minutes or a couple of months.

Z2TT on Sun November 25, 2012 1:33 PM User is offline

If 40 PSI is the static pressure while compressor is not operating, you are seriously low on refrigerant. Basically Rule of thumb if the system does not cool, don't use it it's only doing harm to itself.

If you get the system charged, make sure to get a dye added, to make leaks easier to find. Look for any tell tale signs like dirt buildup on certain parts of condenser, moist sections on hose crimps.
Hose crimped sections that twist. Best way is to get a leak test done to identify all leaks and fix them.

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