i have dual fans that are wired together . they normally come on when the temp guage is about at the half way mark (230 i think) . recently i noticed even when i start my car on a cold morning the fans are already on and never shut off and im afraid it is going to kill my alternator . what tells the computer the car is hot ?
any ideas ? coolant sensor ?

 

ok now im seriously confused . both fans were wired into the primary fan relay and were running all the time like i said in the last post , so i wired them into the secondary fan relay and it is doing the same thing ... wtf ????

the only difference is they come on now with the key on , before the car had to be running ...

 

theres a fan switch in one of the heads, i belive the passenger side toward the back, check to make sure the wire isnt grounded on something

 

thats only for the secondary fan relay. i have it wired up to the primary fan relay, i believe the temp sensor/ecm controls that .

 

I believe if the AC is on the fans come on. Might try checking that circuit.

 

that is also for the secondary fan circuit . i am wired into the primary .

today i replaced the primary relay and the temp sensor and it is doing the same thing , what is left ? the ecm ?? this was working fine for the past yr till recently , i cant figure out what could have went bad ....

 

turns out 89305formula was correct in checking that switch . i unplugged it and the fans shut off and began to work normally (on at about 225*).

if that switch is bad it will trigger both relays to stay on constantly .
i have a 88 iroc 5.7 tpi with dual fans and both fan relays are by the battery with a blk/red + wire on both for future reference .