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Low side in vacuum

rschmitt2 on Mon March 24, 2014 8:02 PM User is offline

Year: 1992
Make: Plymouth
Model: Colt Vista
Engine Size: 1.8
Refrigerant Type: R134
Ambient Temp: 55
Pressure Low: 11 VAC
Pressure High: 65
Country of Origin: United States

Last summer, the AC worked just fine, but it was rarely used over the winter with the defrost. When I turned it on the first time this Spring, no cooling. I put gauges on it and when the compressor kicked on, the high side went to 65 and the low side went into vacuum. Last summer I put in a new condenser, new compressor, new evaporator, and new drier. Can't figure out what could have happened over the winter to cause this problem.

GM Tech on Mon March 24, 2014 8:53 PM User is offline

You lost about 80% of your refrigerant over the winter is what went wrong.......check your charge by recovering and weighing to confirm-- then find and fix your leak.

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......

mk378 on Mon March 24, 2014 9:32 PM User is offline

Leave the compressor off until the high and low pressures equalize and then compare that "static pressure" to the saturation pressure at the ambient temperature (this is the only time you read the temperature scale on the gauge instead of the psi scale). If it is lower, that means that no liquid refrigerant remains in the system-- apparently a major leak has occurred like GM Tech said.

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