Fan Trouble?
Thread Starter
Intermediate
Joined: Nov 2008
Posts: 27
Likes: 0
From: El Paso TX
Fan Trouble?
I always enjoy reading the thread messages. I have a problem with my 1991 corvette, L98 coupe (350 TPI), I have noticed that when the car reaches a 218 TEMP the primary fans start running, the only problem is it won't recycle it stays on all the time. The secondary fan only comes on after I turn on the air conditioning unit. I have taking the vette to the dealer, and the problem still there, many parts where change such as Thermostat, fans relay, Coolant Temperture sensor and refurbished ECM. Can anybody help me solve this mystery? I just can figure it out.
Alex
Alex
Team Owner
Joined: Jan 2003
Posts: 20,292
Likes: 239
From: Summerland B.C. Canada
Is this a new problem or a problem that came with the vette ?
Has anyone checked to see if there is an aftermarket temp switch, tied into the circuit ?
I don't have a schematic for your year, but you would think the dealer would and would be able to track down the source of power/ground.
Has anyone checked to see if there is an aftermarket temp switch, tied into the circuit ?
I don't have a schematic for your year, but you would think the dealer would and would be able to track down the source of power/ground.
Thread Starter
Intermediate
Joined: Nov 2008
Posts: 27
Likes: 0
From: El Paso TX
Yes, this is a problem came with the car when I bought. The ECM was reprogram by the dealer and an after market chip (Hypertech), and a new MEM CAL was installed by the dealer, from the old ECM but the problem of the fan staying on existed when I purchased the Vette and way before the ECM when Bad. I will trace the wires and look for an aftermarket switch installation. Do you think the aftermarket chip could be the problem?
Burning Brakes
Joined: May 2007
Posts: 965
Likes: 13
From: turn 12 at Road America or TX
There's some hysteresis in the fan logic - primary fan on at 218 and off at 208 (? not sure of the temperature). Does the temperature gauge drop while the fan is running? If not, it probably won't shut off until you go over 35 mph or so - its operation is related to vehicle speed also. There are probably other fan logic input / output parameters I don't know about too. Oh, both fans should run when the AC compressor is engaged.
And yes, the ECM grounds the relay coil circuits to actuate each fan.
And yes, the ECM grounds the relay coil circuits to actuate each fan.
Last edited by gbrtng; Apr 11, 2010 at 12:50 PM.
