street demon2k3

i have recently had problems w/ ac after my radiator gave up a week ago. my ac worked for 5 min. then gave out. checked relays, switches, even rigged the compressor to run continuously, but to no use. everything is fine(compressor and switches), then i dissconected my batt. and it worked for a few min. then gave up. i was told i might have to reprogram my cpu because it controls when the compressor turns on or off. any suggestions on what it might be??????????has anyone had this problem???

i live in south tx and its about 103/8x% humidity average and i am toasting in my car. plus leather doesn't help either.

predator

if it is building to much pressure it will do that also if it is low on 134 or maybe your pressure switch is bad ....also those expansion valves go bad regularly ...could be clogged in the core or the condensor put the guages on it and see what pressures are it should run 250 -275 on the high side with A/c on high and 35 on the low side

predator

also the comp will do that if it senses a problem to save the system that is why you had to reset

street demon2k3

i know for sure that the pressure switch is ok(checked it out) had the gauges on it yesterday everything checked out, but i did add a can of 134. the expansion valve i dont know, but there is a sensor on the back of compressor and 2 wires were exposed. i taped it up w/ electrical tape last night. another thing i was told was that with heat and the radiatior giving out it would have melted off the wires sleeve thus causing a short. but that would have burned a fuse or a relay???? ac seemed fine last night but i dissconnected the batt. so i dont know if that was the prob.

predator

well if pressures were ok then expansion valve is good when it goes out pressure will goto like 350 and pressure switch will shut it down

predator

you have a different system than i have i have only one sensor pressure switch on the system mine is by the drier on that line but i think the one you have the one on the comp is the low pressure switch and the one by the drier is high mine acts as high and low or visa versa as far as wich is low and high

street demon2k3

what year car do u have???? yea i got 2 pressure switches one on comp and the other on the top by the cpu. do u know anyone that could help me out. any other suggestions would be very helpful.

predator

what are your pressures after adding the 134 with the fan on high and a/c on max should be 250 on the high pressure side and 35-40 on the loe pressure side....are both switchs ok .....you could put it on the scanner and and with guges at sam time see if your switches are reading the right pressure they should match each other ........i am certified with passenger comfort so i shoul be able to help you out here

SweetZRag

I just went through this last week. You have two sensors that will tell the PCM to lock out the compressor. There is a pressure switch (only 1 on mine) and a temperature switch. If the pressure is too high or too low, the compressor clutch will not engage. There is also a temperature sensor. If the car is cold, I doubt it is a temperature sensor problem.

As somebody said earlier, disconnecting the battery for a few minutes will clear the lockout. Since it works for a few minutes after you disconnect the battery, it seems very likely that one of these sensors or their wiring is the culprit.

The service manual has a good troubleshooting procedure and the schematics will help you check out the wiring. On my car, the blue and black connectors on the PCM contain the pins you are interested in.

I would bet it is the pressure sensor circuit. Put a pressure guage on it and see it the pressure is really out of spec or if the sensor is bad or a short or open in the wiring to the sensor.

The AC clutch relay should have 12 volts on two of the pins all of the time. The signal from the PCM pulls one of the other 2 pins to ground when there is a call for AC. The 4th pin carries the 12 volts to the clutch when the relay is closed. Grounding the pin that goes to ground (The pin closest to the driver's side fender) will force the relay to close to verify if everything else is working and isolate if the problem is the PCM or the wire (dark green with white stripe I think) from the PCM to the relay.

I don't have my manuals with me but if you get really stuck, let me know.

predator

BTW 94 t/a with a german built 396

street demon2k3

dont know the readings w/ the added 134 but i know that switch behind the compressor was shot(two wires bald). i'll try getting the right readings w/ the added 134 and check the switches again along w/ the scanner/gauge test. thanks alot man!!! help is always appreciated.

predator

no prob bro keep me informed if it comes to compressor i got one you can freakin have so let me know but i doubt its compressor

street demon2k3

ok let me get this straight there is one pressure switch, and one temp switch. i am guessing i was wrong about the 2 press. switch thing. but where exactly is the temp. switch??? if is behind the comp that might of been the culprit because of the bald wires. but what if that sensor circuit is messed up what should i do. BTW i know for sure the comp is ok, but i was told by my friend that the comp might not be getting ground thats why it turned on when the relay was rigged to turn on the comp continuously. dont know if its true. now that i recall i switched the fan realy and ac relay i think, and it worked for a min. or so. dont know what that could of meant.

predator

it will work for a minute untill the comp says ok there is a prob and it will shut it down until its reset again....as far as that being a temp switch i think it is another pressure switch like i sid i dont have one of those but i thought the temp switch was in the car is it on the big line or the small line the one by the compressor

street demon2k3

not to sure about the temp switch thing, but there is a pressure switch on a line that is directly on top of the passenger fender well, next to the cpu almost where you bolt up the strut.