My car fan dont turn on when ac is off

ALL THE FANS NEED TO BE OPERATIONAL.

My guess is that your electric fan is NOT operating at all. Under normal conditions, just going down the highway, your cooling system will function just fine without a fan running. The air flow through the radiator is adequate to keep things cool. However, when you stop, you quickly get into an "overheat" situation. Actually, you should be able to hear your fan begin operating when your engine temperature starts climbing or your air conditioner requires the fan to do its thing. Note: If you've ever severely overheated your engine, your problems may be worse than just a fan not running, but you really do need to confirm whether your fan is operating correctly, or not. Another note: I had a vehicle with a tendency to overheat when stopped. It turned out to be a faulty (leaking) pressure cap on the cooling system.

cooling fan not running.check for faulty cooling fan relay or fuse.cooling fan fan should be running when you turn on AC.hotwire cooling fan make sure cooling fan motor okay.

check see if cooling fan running could have faulty cooling fan relay or fuse.if cooling fan dont run when ac on car will overheat.AC COMPRESSOR PUT LOAD ON ENGINE.

GET COOLING FANS CHECKED SOUNDS LIKE A DODGEY FAN OR FAN SWITCH

I assume since it is a GT, you have ac. If you turn on the ac to max with the car running the fan should turn on no matter what the temp of the motor. If it does not, warm the motor up to OT(operating temp). You should here the fan relay click when it wants to turn on. If you dont here the click you might want to check the relay. A seperate fan relay should be under the hood in the power dis. box. It will say what relay it is. If it clicks, you might need a fan motor.....

There is definately a problem with the wiring (i.e.electrical fault).

Let youe electrician run a wire to the fan separately to enable the fun run independently.

Good luck.

Rate this fixya!

The temperature sensor for the radiator cooling fan is probably bad. When you turn the AC on, it overrides the sensor and the fan runs all the time while the AC compressor is engaged.

Cooling Fan Temp Sensor is the First thing You Check (with what you have described) Cooling Fan Should ALways come On When The A/C is turned On as A/C Adds A Load to Engine, If Temp Sensor is Faulty it Will Not Give GROUND Signal to ECM >For COOLING FAN >RELAY to Give ground and turn ON The Fan.
There ARE 2 temp Sensors that Serve Different Purposes 1 is for Dash READING GAGE & Or TEMP LIGHT the Other is For ECM or Fan Relay (SAME Thing) you Said>""can disconnect the sensor and fan continues to run" < This Leads me to think you Changed the Wrong One. Not Questioning your Skills Just Here to Help.
TEMP SENSOR FOR 3.1L V6 is Located upper RH rear of engine compartment, near exhaust system. Temp SENSOR for 2.3L Engine is Located in LH rear of engine compartment.
I Hope this Helps Lead you to a NON-OVERHEATING Pontiac.
Good Luck and Have A Great Evening. rejakwilson

I just had my coolant flushed and my radiator cooling fan replaced. The car was slightly overheating and would "gargle" in the coolant bowl after I turned the engine off. It turned out to be the radiator was clogged up on one side.

I went full tilt and replaced the radiator, water pump, thermostat, radiator cap and timing belt. I have 85,000 miles on the car and it was about time to do these things anyway. It is running like a new car now.