a/c drags down motor help
Thread Starter
Intermediate
Joined: Jul 2009
Posts: 36
Likes: 0
From: Van Horn Tx
a/c drags down motor help
Hello everyone. I have a problem with my 89. When I turn on the A/C it drags the motor down severly, even to the point of killing the engine. It is difficult to restart after this happens. I normally have to turn the a/c off to restart. I've been told that it is probably not sending the extra fuel to the engine. Is there an electrical relay for this? If so where the heck is it? thanks for any help you can offer. By the way the air is cold and seems to blow about as hard as it should.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
I'd try cleaning the inside of the throttle housing/throttle blade first. Sounds like the idle air control valve(IAC) may be bad/sticking. There is no relay to "allow extra fuel'...the ECM controls that depending on sensor input 
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Could be a couple of things: 1. Compressor is shot - remove the belt and turn the outer hub by hand. There should only be minimal resistance. If ok, check the gap between the outer hub and the pulley - should be .020 inch. 2. Compressor isn't controlled by the ECM, but the ECM does receive an a/c on signal from the controls so that it can match idle speed with the load of the compressor. Make sure the signal is there - you'll need a scanner. Turn the a/c on/off and verify that the a/c request on the scanner follows. Then check the IAC counts and injector pulse width. Make sure they rise when the compressor engages. 3. Check the IAC by noting idle speed. Turn it off and restart. The idle should be higher than what you noted, but return to that speed within a couple of seconds.
