Cooling fan does not turn on. Car overheats sometimes when idling for long periods of time. How can I get it to start working properly again

 

I would work out all the easy stuff first. Try changing your thermostats first.

 

How are you positive the car is overheating?

Make sure the fan works, unclip its power connector and jump it with 12V to see if it still functions. If it does get your hands dirty

 

^^^+1.

If applying 12v to test the fan wasn't the first thing you thought out before posting your "what to do" question, I would suggest taking it to a mechanic. Let them test the fan, then relay, then thermostat. That's the best order in terms of cost (when doing it yourself), and if there is a wiring issue, you can usually detect it when testing the relay (after verifying that the fan is still good).

 

Just like everyone said test the fan by itself first ...connect it to your battery. If its working take the next step see if you can find the extra relay and replace it and if u dont have it... go to autozone ( or maybe junkyard ?) and buy one. I got the same problem like you in the past. I changed out my relay and its fixed.

 

Why would you even suggest the thermostat for a fan that doesn't turn on?

Did this problem just start happening?
Have you recently done any engine work? (- including oil change)
Do you have an engine swap?

After you test the fan to battery and verify that the fan does work, plug it back in and go on to test the fan switch.
On the stock motor, it is located on the back of the block above the oil filter.
It is the green one with the two prongs in this image


On newer motors it is located on the thermostat housing


There are two wires that go to this switch.
One wire goes directly to ground at the thermostat housing


The other wire goes to the fan relay.

To test the switch, leave the keys in the ignition set to "on" (engine not running), and unplug the connector to the switch.
Put a paperclip in the connector (not in the switch) and short the two wires together.
The fan should turn on. If it does, then replace the fan switch.

If it does NOT turn on, then hook a piece of wire to a good ground.
Then hook the other end of the wire to the pins inside the connector.
Try both pins - one of them should make the fan turn on.
If the fan comes on, inspect the ground wire for this connector.

If it does NOT turn on, then troubleshoot the relay.