Starting warm engine with A/C on causes "Check Engine Light"?
Thread Starter
Instructor
Joined: Mar 2001
Posts: 199
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From: Canyon Lake California
Starting warm engine with A/C on causes "Check Engine Light"?
Now that the A/C in my '88 is working so much better, thanks to the cleaned out evaporator, a new quirk has developed. This problem may have been present for a long time and we just didn't notice because we didn't use the A/C very much.
If the warm engine is started with the A/C set to "Auto" (Electronic Climate Control), the Check Engine Light comes on about 5 to 10 seconds after starting the engine. If I turn the A/C off and then restart the engine, no Check Engine Light. This is very repeatable.
It seems like the A/C compressor is engaged during engine cranking and it prevents the engine from quickly reaching idle speed. Also, the engine is a little harder to start with the A/C set to "Auto".
Has anyone else had this experience? Any suggestions - besides "turn off the A/C before starting the engine"? 8~)
Thanks in advance for your feedback.
Greg S. / Canyon Lake, CA.
[Modified by Greg's '88, 4:04 PM 6/16/2003]
If the warm engine is started with the A/C set to "Auto" (Electronic Climate Control), the Check Engine Light comes on about 5 to 10 seconds after starting the engine. If I turn the A/C off and then restart the engine, no Check Engine Light. This is very repeatable.
It seems like the A/C compressor is engaged during engine cranking and it prevents the engine from quickly reaching idle speed. Also, the engine is a little harder to start with the A/C set to "Auto".
Has anyone else had this experience? Any suggestions - besides "turn off the A/C before starting the engine"? 8~)
Thanks in advance for your feedback.
Greg S. / Canyon Lake, CA.
[Modified by Greg's '88, 4:04 PM 6/16/2003]
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Starting warm engine with A/C on causes "Check Engine Light"? (Greg's '88)
Dash assembly sends a 7 volt signal (electronic air - 12 volt if manual) to the ECM when a/c, bi-level or defrost is requested. ECM then increases IAC counts raising idle to match compressor load. Neither the IAC or the a/c circuit is on the driver circuit that controls the Check Engine Light, so assuming there are no trouble codes, sounds like an ECM fault.
Le Mans Master
Joined: Jun 2002
Posts: 6,097
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From: High Plains Drifter Fayetteville, AR
Re: Starting warm engine with A/C on causes "Check Engine Light"? (SunCr)
Try pulling the codes and see what you get? Not sure how to start troubleshooting this one :confused:
Thread Starter
Instructor
Joined: Mar 2001
Posts: 199
Likes: 0
From: Canyon Lake California
Re: Starting warm engine with A/C on causes "Check Engine Light"? (SunCr)
This weekend I will pull the codes to see if any are stored. I will post the results here for anyone else having a similar problem.
Thanks for the feedback.
Greg S. / Canyon Lake, CA.
Thanks for the feedback.
Greg S. / Canyon Lake, CA.
