Radiator fan won't run?

[jms92]

Picked up a LeSabre for my sons first car. It's a 1990 with a 100K on it. It is overall in good shape it just has alot of little issues to be repaired on it... The radiator fan motor won't run. It's runs when I jump 12 volts to the motor. I metered both the high and low speed relays and they meter OK. The fan will run when the AC is put on. It just won't start when the engine heats up like it should. My guess based on a manual for another car is: 1) the temperature sensor --where is it and how do I check it? (theres 2 stemp sensors right? one to signal over heat/ temp light on dash, and one to start fan... 2) The PCM --how do I get at it? 3) a bad wire that picks the relay to start the fan-- I hope not.... Any input or help is greatly appreciated. Where trying to keep repair costs to a minimum...

Thanks... Jayme...

[yogi_123rd]

You problem is either a relay or the temperature sensor switch.

You have two identical radiator fan relays located on the driver side fender wall in the engine compartment near the radiator. One is for low speed fan operation (i.e comes on when the AC is on) and the other is for hi speed (engine coolant hot). On my 90 Lesaber, the relay on the inside is the low speed one

To test if the relay is the problem: Swap the hi speed with the low speed relay (the relays are the same part number) and turn on your ignition and AC. If the fans do not run using the other relay, the relay is your problem.

If the both relays run in AC mode, the temperature switch may be bad. It is located immediately above and behind of the throttle body in the intake manifold area (in a nook where only two fingertips can reach). To test: Remove the connector to the plug and jump a wire between the sockets in the connector. Turn on your ignition to run. The radiator fans should come on at high speed. If they do, the temperature switch is likely your problem. If they don't, the wiring or ECM is faulty as you should already have verified the relay is good.

[jms92]

I need some help here, this &#*%)(# problem is getting old. I thought I had this fixed... We replace the temperature sensor and that did not fix it... I metered both relays and they metered good. I could put 12 volts right on the fan motor and it starts right up. The fan motor use to kick on when we put the AC control on high... In desperation I swapped out a relay and the problem appeared to be fixed for about 6 monthes... Now it's back! I replaced both relays and no fix!!! Fan will no longer kick on with the AC control switched to high... What's next the ECM module??? I hate to guess wrong on that... Is there anything Else I can check? I'm almost thinking about just running a switch from the battery terminals directly to the fan motor and turning it off and on with the car. Would there be a reason not to do this???? Or is there somewhere else I could grap 12 volts from that comes on and off with the engine???? PLEASE help!!!!! This car is a junker that gets my 17 year old back and forth to school and work, I hate to put a lot of $$$ into it.....

[maxwedge]

The fans will not come on with the ac if the air temp is below 40 F, that is the lowest temp the ac will work ,as well as the fans coming on with the ac, naturally. Engine temp must reach 222f to trigger the fns normally.

[jms92]

I confused but maybe I can learn something here... I removed the wire from the temperature sensor, started the car and the fan comes right on.... Car would start a little hard and the check engine light comes on...

So I put a jumper wire on the wire and the fan runs continually w no check engine light... so far so good....

I reinstalled the original senser thinking possibly the new one had a short in it. and its the same deal... Right now we will just run the car with the temperature sensor wire unplugged with a jumper in it...

What's up here?? Could the original and new temperature senor be bad?? I think I will put a meter on the sensor I have out and check it. The heat it up to see if the switch closes...??? This is why I hate working on cars. This should have been a simple problem and a simple fix, but it never is for me and all the lesson are learned the hard way....

[maxwedge]

Simple here, reconnect properly, get a scanner on it, let it idle till the temp reaches about 222 see if they go on. The disconnect jump issue shows all is working as far as the pcm and wiring, what you are getting is normal.

[jms92]

I don't have a scanner.... How long do you think it takes to get the car temperature up to 222 degress? I had the car running for about 10-15 minutes and I drove it around the block for about 4 miles. Came home and the fan wasn't running yet but I never get a temperature light.. Maybe it just take longer to raise the temperature than I'm thinking...

[maxwedge]

Takes quite a while at idle for this temp, depends on your outside temp also. Don't drive it this will not raise the temp enough to trigger the fans.

[stuzman]

Originally Posted by jms92

I don't have a scanner.... How long do you think it takes to get the car temperature up to 222 degress? I had the car running for about 10-15 minutes and I drove it around the block for about 4 miles. Came home and the fan wasn't running yet but I never get a temperature light.. Maybe it just take longer to raise the temperature than I'm thinking...

Maybe the fan circuit is okay and the temperature of the coolant just hasn't got hot enough to swith it on. Why are you sure that something is wrong with the fan circuit? Just trying to look at other sides of the equation.

[auto trainy]

Stuzman has a good point,maybey you need a thermistat,have you checked the temperature of the coolant?