ac at idle
Instructor
Joined: Sep 2006
Posts: 220
Likes: 0
From: Castleton NY
When your AC kicks on, it puts additional load on your engine. You idle may be surging to keep the RPMs up? Does it race when the A/C is on and idling? Or does it just raise a little (it is supposed to do that)
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
There is a voltage signal from the dash controls to the ECM when a/c is requested and the ECM raises IAC counts to allow for the load of the compressor. Best to troubleshoot with a scanner as you observe compressor engagement as it will show you the request signal and the IAC counts. Otherwise, the signal comes in at ECM terminal B8. It will be 12 volts with Manual Air; about 6 volts with Electronic.
