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Gauge reading

johnboy123 on Fri March 29, 2013 6:44 PM User is offlineView users profile

Year: 2003
Make: Dodge
Model: Caravan
Engine Size: 3.3
Refrigerant Type: R-134
Ambient Temp: 70
Pressure Low: 90
Pressure High: 0
Country of Origin: United States

Compressor is NOT engaging. Front AC equipped only. Txv type. Verified correct manifold hose placement. Is this the "look" of a low charge? Does the reed valve of the compressor or txv system "lock" the remaining gas in the low pressure side? Any thoughts would be appreciated.

mk378 on Fri March 29, 2013 7:19 PM User is offline

Your high side hose is not opening the valve to the car. There is no way for high side to be lower than low side, since the check valves in the compressor open to flow that way.

Regardless of that, with 90 psi low side, the compressor should engage. Seems to be an electrical problem or the clutch gap could be too wide.

GM Tech on Fri March 29, 2013 7:21 PM User is offline

It's the look of a high side coupler on your gage set not communicating with the system- probably not depressing the ball valve enough, or properly. 90 psi static system pressure is enough to turn on compressor- so you may have an electrical issue. 90 is high for a static cold engine- at 70 degf amnient. probably just right for a hot engine.

You can't tell if it is undercharged by static pressure alone- needs to run, or have system charge extracted and weighed.

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......

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