I recently installed a Low Temp. electric cooling fan switch in my 86. Now the fan runs all the time although it should only run when temp. reaches 200 degrees. Need Help Please.

Is it the switch that goes in the head? What temp. thermostat are you running? I used one on my old trans am, it had a wire skinned and grounded out against the motor causing fans to run constantly.

Yes, Switch is in the left head Thermo. is 180 and only one wire goes from switch togreen/White wire ro fan relay

Thats the same as mine was.It is the ground. When the water reaches 200 degrees it closes a contact in the sender/switch that grounds the fan relay and completes the circuit to close the fan relay(turns the fans on). You might want to check wiring again for breaks or skins. Bare wire touches any metal= fans will run. I hope this is useful and not too confusing.

As dailydriver said, when the switch in the head closes at the spec temperature, it grounds and closes the circuit of the primary side of the auxiliary fan relay. If the fan runs constantly, either the switch is shorted or there is a short in the wiring between the switch and the relay.

Also, you didn't actually say, but realize that this switch can only affect auxiliary fan on and off temps. If the main fan is coming and staying on, someone before you has modified the wiring. The main fan is computer controlled and this switch shouldn't affect main fan operation in any way.

RACE ON!!!

Thats the same as mine was.It is the ground. When the water reaches 200 degrees it closes a contact in the sender/switch that grounds the fan relay and completes the circuit to close the fan relay(turns the fans on). You might want to check wiring again for breaks or skins. Bare wire touches any metal= fans will run. I hope this is useful and not too confusing.

Fully agree with your assesment on this issue.:cheers: