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Coolant fans running

I have a 2001 Firebird V-6 and when I start the engine all 3 cooling fans turn on and run until I turn off the car. Also, the temp gauge doesn’t work but the heater seems to work normally

Do you have the defrost on? Or is it an automatic HVAC system?

You could have a bad temperature sensor or a computer problem etc. Maybe someone who knows 2001 Firebirds may be better able to help.

Does your check engine light ever come on?

“…the temp gauge doesn’t work…” Please elaborate.

Make sure the A/C is off, and the heater controls are NOT set on “defrost”.
If the fans still come on, go under the hood and replace the ‘fan’ relay with one of the other relays which fit (maybe, the ‘horn’ relay). Result?
Reconnect the wire to the engine coolant temperature sensor, on the engine. It looks like this: http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c152801e8fbc

The fact that the temperature gauge isn’t working may be unrelated to the fan problem since the coolant sensor used for the fans is usually a seperate sensor than the gauge sensor. You should get the gauge working though since it is important to know how hot the engine is running.

The fans are controlled by the PCM and a coolant sensor. I would first check to see if that sensor is working like it should be. If that is ok then the PCM may have a fault.

This is the description and operation of the cooling fans from ALLDATA. I can’t find a location for a third cooling fan. Is there one in front of the radiator?

You need to get into the ECM and look at the live data, I would be interested in knowing what the ECM sees for a engine temp when the fans are running.

The engine cooling fan system consists of two electrical cooling fans and three fan relays. The relays are arranged in a series/parallel configuration that allows the Powertrain Control Module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage, from the underhood fuse block. The ground path is provided at G106.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan 3 relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan 3 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 3 relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 3 relay coil is energized closing the relay contacts and provides battery positive voltage on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

L36
The PCM commands low speed fans on under the following conditions:

Engine coolant temperature exceeds approximately 105?C (221?F).
When A/C is requested and the ambient temperature is greater than 10?C (50?F).
A/C refrigerant pressure exceeds 1310 kpa (190 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?C (284?F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands high speed fans on under the following conditions:

Engine coolant temperature reaches 113?C (235?F).
A/C refrigerant pressure exceeds 1896 kpa (275 psi).
When certain DTCs set.
LS1
The PCM commands low speed fans on under the following conditions:

Engine coolant temperature exceeds approximately 108?C (226?F).
When A/C is requested and the ambient temperature is greater than 10?C (50?F).
A/C refrigerant pressure exceeds 1482 kpa (215 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 140?C (284?F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.
The PCM commands High Speed Fans on under the following conditions:

Engine coolant temperature reaches 112?C (234?F).
A/C refrigerant pressure exceeds 1710 kpa (248 psi).
When certain DTCs set.