main fan comes on when car started
Thread Starter
Drifting
Joined: Oct 2006
Posts: 1,328
Likes: 14
From: Stafford Connecticut
main fan comes on when car started
I am trying to find a reason my main fan comes on when I start my vette.I did the tests in the factory manual and still can't figure it out.If I turn the key to the on position, motor not running ,and disconnect the wire from the the temp sensor and ground it the fan will not come on.if I turn the motor on the fan will turn on.If I disconnect the relay it will turn off.I have checked the wire from the harness and it's not grounded anywhere.If I do the same test on the auxiliary motor it works properly.One more thing the fan will sometimes shut off for a moment then come back on even though the motor is cold and just started.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Main fan is controlled by the computer ; not a temp sensor
Only the Aux fan ( if fitted ) has a seperate temp switch
Is the plug on the A/c line pressure sensor correctly
Team Owner
Joined: Jan 2003
Posts: 20,326
Likes: 252
From: Summerland B.C. Canada
There are a few things that will cause main fan to run, grounding the gauge sender is not one of them.
Limp home mode, is the SES light on ?
AC, Is climate control on defrost ?
Is A and B jumped at ALDL connector ?
Is there a short to ground on circuit 335 ?
Limp home mode, is the SES light on ?
AC, Is climate control on defrost ?
Is A and B jumped at ALDL connector ?
Is there a short to ground on circuit 335 ?
Thread Starter
Drifting
Joined: Oct 2006
Posts: 1,328
Likes: 14
From: Stafford Connecticut
None of those things are happening Agent 86.I did try and switch the relays no change.Sometimes when I start the motor the fan won't come on at first for a few minutes then it will come on then go off and then come on again before it gets up to temp.Very strange.Thanks for the suggestions guys I will keep looking for a solution.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
I am trying to find a reason my main fan comes on when I start my vette.I did the tests in the factory manual and still can't figure it out.If I turn the key to the on position, motor not running ,and disconnect the wire from the the temp sensor and ground it the fan will not come on.if I turn the motor on the fan will turn on.If I disconnect the relay it will turn off.I have checked the wire from the harness and it's not grounded anywhere.If I do the same test on the auxiliary motor it works properly.One more thing the fan will sometimes shut off for a moment then come back on even though the motor is cold and just started.
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Thread Starter
Drifting
Joined: Oct 2006
Posts: 1,328
Likes: 14
From: Stafford Connecticut
I never looked to see if the computer had an other than factory chip.The previous owner never mentioned it.He was pretty specific on the changes to the Vette.He gave me all the receipts he had.
Thread Starter
Drifting
Joined: Oct 2006
Posts: 1,328
Likes: 14
From: Stafford Connecticut
Sailorsteve I have read and reread the factory manual.I did the tests in the manual still can't find if it is working right.My 85 and 86 did not work like this maybe 88 is different?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
There could be an issue with the coolant temp sensor (the one on the front of the intake - not the one in the head that the cluster gauge uses) the computer uses to trigger the the main fan relay.
Thread Starter
Drifting
Joined: Oct 2006
Posts: 1,328
Likes: 14
From: Stafford Connecticut
Corvette0096 I was going through the folder of parts and repairs that I got with the Vette.I found a print out dealing with a fan conversion kit.I do not have a receipt for the kit .The Vette came from Texas where it gets pretty hot so the previous owner could have changed the way the fans operate.He also put in a high flow water pump and Robert shaw thermostat.All the fan wiring looks stock so I'm still perplexed.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Corvette0096 I was going through the folder of parts and repairs that I got with the Vette.I found a print out dealing with a fan conversion kit.I do not have a receipt for the kit .The Vette came from Texas where it gets pretty hot so the previous owner could have changed the way the fans operate.He also put in a high flow water pump and Robert shaw thermostat.All the fan wiring looks stock so I'm still perplexed.
