Ok here's my situation..my '05 GT has had intermittent AC problems since I bought it, where the AC compressor would engage sometimes, and at most of the time not at all.

I've done the following things: Checked pressure, in "red" zone (Compressor not engaged)
*Checked voltage @ Cycling Switch, 14v
*Checked voltage @ Dual Function switch, 14v
*Checked voltage @ Smart Junction box, 14v
*Replaced relay,no effect
*Replaced Dual Function switch, no effect
*Jumped harness on cycling switch, no effect.


After messing around with the relay in the junction box, the compressor kicked on. Did not find any issues with wiring. After compressor engaged the low side gauge would drop to ~15PSI (disengaging the compressor). After pressure would rise the compressor would re-engage. Ambient temperature approximately ~55*. I added refrigerant to the system raising the pressure to 25PSI and staying consistant (took 2 cans). Is it possible the system would not allow the compressor to engage due to low refrigerant even though my gauge reading with the compressor off was ~60PSI?

Any help is appreciated!

 

You are/were most likely low on freon. The low side pressure will drop below the point where the low pressure safety switch will cut the system off. The outside temperature will also affect the system somewhat. If you have a good thermometer, your outlet vents should have a 20 deg. or more drop below cabin temperature. Find a temperature/pressure chart for the car to find out what your pressures on the low/high sides should be.

Frank