ok so i have been having a issue with my radiator coolin fans they will not turn on unless i turn the a/c on things i have done new ects new relays and thermostat they work if i turn the a/c on they go to high speed and cool the engine down if i dont turn the a/c on they dont turn on and the tempature gauge goes to high the moment a/c is turned on both fans kick on full speed and immeadiatly the tempature gauge drops to half way any suggestions? need help

 

Are you stating that the fans only operate at high speed with the AC turned on? If they don't operate at low speed then check out FAN1 relay located in front of the battery. FAN1 relay operates both motor fans at low speed, while the FAN2 relay operates motor fan 1 at high speed, and the FAN3 relay operates motor fan 2 at high speed.

To check FAN1 relay swap it with another relay. If the fan motors now operate at low speed with the AC turned on then that relay is defective.

To test the fan motors apply 12V directly to their connectors.

 

+1. Also, I am curious as to why you replaced your relays? Were they defective? Also, where did you get the replacement relays??

 

i swapped relays around from my parts car

 

yes they only operate at high speed if the a/c is on both fans kick on at low speed but just for a second with the a/c off ill will do some more trouble shootin this eaving

 

Maybe this will help you.

When things are working properly:

When you start the car and the engine is cold and the air conditioning is OFF, fans should not run. When the engine temperature reaches 200 degrees, both fans run at low speed. When engine temperature reaches 220 degrees, both fans run at high speed.

When you start the car cold and you turn the air conditioning ON, both fans run at low speed. When the engine temperature reaches 200 degrees, both fans run at high speed.

Pin 14 of the ECM goes to 0 volts, activating Fan Relay 1 which sends 12 volts to pin 1 of both fan motors, the low speed winding. Pin 4 of the motor is the ground.

Pin 13 of the ECM goes to 0 volts, activating Fan Relays 2 and 3. Fan Relay 2 controls fan motor 1, while Fan Relay 3 controls fan motor 2. The fan relays send 12 volts to pin 2 of the fan motor, the high speed winding. The fan relays also connect the fan motor pin 3 to ground.

On the fan motor connector:
pin 1 is a white with black stripe wire - low speed 12 volts
pin 4 is a black wire - low speed ground.
pin 2 is a white with blue stripe wire - high speed 12 volts.
pin 3 is a white with red stripe wire - high speed ground.

The ECM uses a water temperature sensor in the engine to determine when to turn on the fans. Also note that there are 2 water temperature sensors in the engine, one for the ECM and one for the dash gauge.