A while back my car got hot. I found that the cooling fan wasnt coming on. I was checking the fan switch that screws into the block and noticed that the plug was in really bad condition. I soldered on a new pigtail and hoped that would correct the issue. It didnt. The fan DOES work when the a/c is turned on. So i dont believe the fan is the issue nor the fan switch in the block. That only leaves the wire itself and the relay correct? I read that its common for the relays to burn out. My question is would the fan still oporate when the a/ c is switched on if the relay was bad?

 

I believe it's supposed to work that way just in case the relay fails while you're on a drive you can turn on the a/c to keep the engine from truly overheating until you can identify issue and fix. I just did troubleshooting on my cooling fan and was successful so I'll ask...

1. With a fused jumper wire between RED wire & BLK/RED wire of the relay connector did the fan come on?
IF yes to # 1
2. Ground the fan switch connector, did the fan come on?
IF yes to # 2

break out the infrared temp gun and make sure it's truly hot enough to activate the fan switch. Mine doesn't kick on until about 235ish...

 

I could be wrong but I think the fan temp switch in the head has no effect on whether or not the fan comes on when you turn on the air conditioning.

Put the key in the RUN (don't start the car) and run a wire from the temperature fan switch plug to a ground and see if the fan comes on. If it does then the temp switch could be bad. If it doesn't come on then you should start checking the relay.


*edit*
beat by 92RS

 

Define hot? Stock turn on temp is something like 220-230*. With the exception of idling in bumper to bumper traffic in summer heat or exceptionally slow drive-thru lanes, I seldom hear the fans kick in. 99% of the time the car is moving and the airdam handles the air flow through the radiator.

 

Drew. I let it get HOT because I know the factory setting is higher. I let it get up to 250 before I hit the a/c to get the fan going. it doesn't come on without the a/c on.

 

Was the 250 measured w/ a infrared temp gun? What happened to the actual troubleshooting procedures myself and other members pointed out, completely disregarded?

1. With a fused jumper wire between RED wire & BLK/RED wire of the relay connector did the fan come on?
IF yes to # 1
2. Ground the fan switch connector, did the fan come on?
IF yes to # 2
Replace the Fan Switch

 

The fact that the fan turns with the AC tells you that the relay and fan are good. The AC control sends a negative ground to the same green with white stripe wire that the fan switch goes to. You need to test to see if you have continuity from the connector at the fan switch to where it connects to the fan relay. If you do and grounding that connector with key on turns on the fan then the fan switch is defective. There aren't that many parts to this for it to be complicated. Check these things
Also should unplug the fan relay and check for any less than good connections there

 

no I was using the temp gauge .i don't own an infrared gun. the car was acting like it was overheating. I wouldn't swear to the accuracy of the stock gauge but you can tell when they are running hot. I haven't disregarded and of this advice. Im still working on it. I feel like I will be able to get to the bottom of it and correct it with all of the suggested diagnostics offered.

 

1st, let me apologize if I came off like a DB, 2nd you're going to need an aldl cable OR a temp gun. Today while datalogging my gauge read at the 3rd line... No fan...looked over at my laptop, ECM only saw 218F which isn't hot enough to activate the fan. My suggestions came right out of the GM Service Manual so if you can spare an hour you'll have it diagnosed and fixed in no time buddy!