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I've got a 96 SSEi pushing 293K miles. I noticed the air no longer works but worked great a couple weeks ago. I can bypass the AC Compressor relay and turn the compressor on. I tried a new relay and no luck. I think it may be that the A/C request signal is not making it to the PCM. I want to see if there is any voltage on the A/C lines from the HVAC Programmer to the PCM. From the probing I've done so far, it doesn't look like the PCM is allowing the A/C Compressor relay to activate and it gets it's request from the HVAC programer. I haven't ruled out the HVAC control module but everything else works except the A/C (no compressor on defrost either). My question is where is the HVAC Programmer located? I don't know which module it is behind the passenger I/P.

Thanks

rkball wrote:My question is where is the HVAC Programmer located? I don't know which module it is behind the passenger I/P.

Thanks

It is the black plastic box that has all the colored vacuum lines going to it. On my 93, it is right of the heater box/air mix assembly and left of the PCM.

The compressor will not engage if it senses too low of a pressure in the AC system. Try pumping some freon in ( and or check the pressure left in the AC line )

Thanks. I did think about the line pressure but I don't have the tools yet to check it out. This car has the pressure transducer feeding a signal to the computer. Not the limit pressure switches like earlier models. It's easy to check a switch but a bit harder to check a pressure transducer putting out an analog signal. I am not sure what level of signals should be present on the pressure transducer and what wire is what. There are three wires coming from this transducer. Anyone know what I should measure from this sensor, in the refrigerant line just off the compressor (right front of engine)?

Don't worry so much about measuring the output of your pressure transducer, worry more about actually measuring your AC system pressure. Just buy/borrow/ or rent a pressure gauge and stick it on the high side schrader valve. Turn on the system, jump your relay and measure it.