What controls the fan to turn on???

[geoffinbc]

Gm usually has the fans turn on at 108*C

[GRANDFURY]

Well I replaced the temp sen and the fan still wont turn on. Could this be thermostat related?

[StudlyCamaro]

thermostat just controls the coolant going to the radiator

[Manitcor]

maybe but ive heard that it could be a problems with the ECU itself, sotty I havent gotten pictures yet, im doing some work on the car tonight so I should be able to grab some then

[GRANDFURY]

ECU? Do you mean ECM? If not what is a ECU?

[GRANDFURY]

Also if coolant could not get in the engine how could the temp sensor know to turn the fan on?

[v6h.o.]

the Fan will not kick in untill the coolant is in the range of 205-215*F IIRC. it will not come on untill the sensor see's the exact temp for the commanded state.

[Anonymous]

Also if coolant could not get in the engine how could the temp sensor know to turn the fan on?

There is coolant in the engine. If you thermostat was bad (and it wasn't a fail-safe thermostat) it would block hot coolant causeing it to back up in the coolant reservior and come out the little hose that goes to the bottem of the car (or steam). So regardless if your thermostat is bad or not, it doesn't control the temp sensor and the fan.

[GRANDFURY]

Replaced the stat and she runs cool as shit now I still dont have the fan relay I had hooked up but she runs GREAT. She stubbles off the line for a half sec but when she catches it spins the tires and goes like shit it shifts smoother now and the gas is back too normail use. Oh yeah my speedo is right now I"M SO HAPPY the prix is back. Thanx for the help guys.

[SappySE107]

There are 2 temp sensors, one in the head and one in the lower intake. One goes to the gauge in the car, and the other to the ECM. The fans turn on stock at 106 degrees celcius, for the 3.4 DOHC anyway. The 2.8 is set at 104 degrees and 106 for the 3.1.

[Manitcor]

ok, here are the pics for my version of the "Fan Mod"

Ive only done this to my passenger side fan so far, I plan to do it to the drivers side this spring. Not much use for it this time of year.

[wiccanferret]

On mine the switch was on the ground, so I just ran another ground to the dash and stuck a switch up there (using a fuse in the fusebox right beside it, of course). This way when I'm out prowling, the damn thing doesn't come on right as the light turns green. I've gotten around .15 difference in the 1/4 by turning it off as opposed to having it on. This will also allow you to turn it on without the car running if you want to cool the engine off quickly.

[Manitcor]

hmm ill have to see the diff in a track run between fans on and off, i could imagine a small diff but not a full tenth and a half

[Guest]

My fan would'nt turn on either so i replaced the fan relay and coolant temp switch and that still did'nt work