A/C will not come on. Took it to a small mechanic(mistake) and replaced a transducer and evap temp sensor. A/C comes on for about 15 seconds and shuts off and will not come back on. Dealer did diagnostic and said evap temp sensor is bad. Replaced it again and got the same results. What would cause this? Is the evap temp sensor even really necassary? Mechanic suggested bypassing it, I don't want to do that.
Any suggestions?

 

Twice diagnosed the same problem. Twice it didn't work? I doubt that's it. Now.... perhaps there is some sort of electrical problem that blows that sensor every time you get it working again? A shorted out wire? Have you replaced any fuses lately? Did you replace it with the same amperage fuse? I would get a good electrical guy to look at it.....

My ac problem involved the front blower not working. The ac control unit was working correctly but the blower just wouldn't come on. To be even stranger the rear ac worked fine. That turned out to be the "blower module" which I thought was a blower resistor until I got to the dealership and spoke with the parts guy. There are so many electronics on that board in side the blower module that you might check and see if that's your problem.

A big clue would be if your compressor is still cycling on and off when you have the ac on. If that's happening the freon should be cold (barring a leak in the system). Thus if the blower is working you should get cold air.

Try to look at the problem from a perspective of what is working and go from there.

 

OK when u say AC do u mean the cold air or the air all together not comming out of the vents? If u bypass the sensor then the evap will freeze up and u will haft to wait for the thing to unfreeze b4 it will work again so NO. Need to see ac pressures when running. U said they replaced the temp sensor right?? Thats on the H block outside of the car near the firewall is that what they said they replaced???

 

Yes, I mean cold air. The compressor will not come on. The blower works fine. Yeah, the dealer said there prolly is a short or the BCM is bad. The evap temp sensor thats located on the expansion valve is what goes bad. It will work for about 15 seconds and then the compressor will shut off. Then when they check the sensor, they say it is sending the wrong voltage to the BCM., causing the compressor to shut down. The mechanic said if we bypass the evap temp sensor, the (transducer??) would shut it down before it froze up. Is that correct?

 

nope it would only turn it off if the pressure gets to high or low the evap temp sensor is juft for the evap not freezing up they cycles the compressor to turn off and on so that the compressor does not freeze up and make no air come out. The high and low side switch is for plumbing issues if the compressor will not unlock and keep running and the pressure gets above 450 then that turns off the compressor or if there is not enoughfreeon and pressure is to low that will turn off the compressor. ANd i hate to tell the dealer that u went to but the sensor goes into the Auto Temp control head then bussed out to the PCM to turn off the compressor. Here is the wire diagram look for yourself.

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A/C will not come on. A/C comes on for about 15 seconds and shuts off and will not come back on. Dealer did diagnostic and said evap temp sensor is bad. Replaced it again and got the same results. What would cause this?
Any suggestions? have any clue where i can get a diagram of a/c wiring

 

well there is to many pages of wiring just to post. IF u say it is cold for 15 seconds then cuts off can u cycle the key and it does the same thing or do u haft to wait for ahile b4 it will come on for 15 seconds. Does the ac light stay on the whole time or does it go off? if u can cycle the key and it comes back on I would say cheap route replace the ac pressure transducer first. or if u can reach it get a screw driver and a hammer with the car running ac on give the ac clutch a good wack and see if it comes on and stays on. be carefull if the clutch comes on it will throw the screw driver at u if u dont move it fast enough.
SO try the clutch deal first then the transducer next. More then that would be out of your hands with out having access to a DRB and can see if the ac request is comming from the control head into the IPM and form the IPM out to the clutch.

 

when the clutch turns on for few seconds and turns back off it dosent blow the cold air. but i got wires connected straight to the clutch and put swich inside a car. when i turn the ac on and then turn the swich on that i connected straigh to the ac clutch the ac works good. so i dont know maybe its somethingwrongwith the ac swich. wat else can it be

 

ok u have a control issue then.Some thing is telling the pcm not to turn on the ac clutch like the pressure transducer or the IPM it self has an internal issue. Replace the pressure switch and go from there

 

u mean the whole swich?