Expert: Roland Finston - 6/18/2011

Question
QUESTION: AC will not come on at all with switch on the dash. If you by-pass the relay it will come on, but condenser fan will not run.
AC seems to work correctly otherwise. Any suggestions?

ANSWER: Hi Rosemarie,
I would first wonder if the refrigerant level is below the minimum to satisfy the pressure requirements to activate the compressor clutch. It could be electrical, but without know the year/make/model/body style/engine I can't suggest a fuse to look at. Or it could be the relay. The fan won't come on though without the computer being satisfied that the AC has enough refrigerant in it. So that is where I would begin.
Roland
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Thank you


---------- FOLLOW-UP ----------

QUESTION: It's a 1997 Chrysler Sebring convertible, engine 2.5 v6.
Fuses are good. I can active the the relay and everything works, the refrigerant level is fine. The relay is ground activated and I'm getting no ground.

Answer
Hi Rosemarie,
The relay is grounded by the powertrain controller via the dark blue/orange wire from pin 64. I would believe it would ground it if it saw your request for AC and if the pressure in the system were suffincient. So check the wire for continuity and also check that the A/C illunmination light at the switch on the heater control panel is illuminated when you request A/C. If not, then perhaps the switch is faulty or the illumination lamp is burned out as it is necessary for the body controller at pin 16 of the white 22-pin plug to 'sense' that you have requested A/C.
The effect of requesting A/C is to ground the far end of the light whose near end is connected to that pin of the body computer and which is then noticed by the body computer.
Roland
Please "rate" my answer, and where you see the question about a nomination of me to be 'volunteer of the month' consider giving a 'yes' response.
Thank you