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Engine's idling

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New User

Dec 3, 2016, 10:12 AM

Post #1 of 4 (768 views)
Engine's idling Sign In

My name is Gustavo Woltmann, working with the team of publishers and I have a 1994 Toyota Corolla Gli. I just want to ask regarding my car's idling. Everytime I turn the a/c the idle goes down. What can I do to avoid this?

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 3, 2016, 1:54 PM

Post #2 of 4 (758 views)
Re: Engine's idling Sign In


The AC compressor applies an extra load on the engine which automatically brings the idle down.

The computer should automatically bring the idle up a little to compensate for that but there may be issues with the throttle body.

You can try this

First eliminate all vacuum or air leaks in the system (very important)

. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 4, 2016, 5:36 PM

Post #3 of 4 (740 views)
Re: Engine's idling Sign In

Some of the older Toyotas, like yours, has a computer controlled idle up vacuum switching valve for the ac that will open and create bypass air around the throttle to idle the engine up. If the solenoid doesn't open when commanded for some reason, the engine speed won't idle up to compensate for the ac compressor load.

It might look something like this.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Dec 4, 2016, 5:46 PM)

New User

Dec 5, 2016, 2:03 AM

Post #4 of 4 (720 views)
Re: Engine's idling Sign In

yes thats exactly what i have here in my car's engine bay. thanks so much, this is a big help for me!

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