wiring problem

Asked by Feb 19, 2017 at 03:52 PM about the 1996 Pontiac Sunfire 2 Dr GT Coupe

Question type: Maintenance & Repair

every time o turn on the ac or defrost the engine revs above 2500 rpm and
stays there. if i turn off the a/c or take the selector off off defrost the rpm
returns to normal. Any ideas?????

1 Answer


Faulty IAC (Idle Air Control) valve. When air conditioning and defrost are selected the computer is supposed to speed up the idle about 500 RPMs to prevent stalling from the added load of the air conditioning compressor. Sounds like the IAC is opening up too much and so the idle goes up more than it's supposed to. HTH. -Jim

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