Why does my car keep overheating when the AC or heat is turned off at ldle.

SPETERSEN8

MEMBER
1996 CHEVROLET CORVETTE
40,000 MILES

The car keeps overheating at idle wnen the ac or heat or turned off. But when you turn either one on then the electric fan kicks in like it's suppose to. I've replaced both the fan relay switch and the temp sending sensor switch to no avail. Thank you Steve petersen.

6 Replies

DOCFIXIT

MECHANIC
18,828 POSTS

There are three fan relays was #1 replaced? If yes maybe wiring to PCM or PCM

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Tuesday, October 11th, 2011 AT 7:39 PM

SPETERSEN8

MEMBER
4 POSTS

The reply from Docfixit might help. I replaced only one relay down underneath the hood on the driver side by the left front headlight assembly. I will locate the other two and try replacing those and see if that helps. Thanks.

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Tuesday, October 11th, 2011 AT 9:20 PM

DOCFIXIT

MECHANIC
18,828 POSTS

All three are located in same place take new one and swap it around

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Wednesday, October 12th, 2011 AT 2:01 PM

WRENCHTECH

MECHANIC
20,761 POSTS

You may not have a problem at all. Those fans are programmed to come on at much higher temps than what you would expect. That is deliberate. I believe low speed doesn't come in until abut 226 and high is over 230 degrees.

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Wednesday, October 12th, 2011 AT 2:20 PM

SPETERSEN8

MEMBER
4 POSTS

Thanks for the information from docfixit and wrenchtech. Iwill try the process of elimination and I'll let the car run a little longer and see if the fan kicks in at the higher temp. I've had the car for five years and never had this problem before. Thank you for your help. Steve.