First things first. Don't tell me to do a search because I have, on many different websites (4 hours and counting).

The problem is my rad fan won't come on at all. Not when I'm overheating, not when the A/C is on, never. I have checked the fan and it works. I've checked the relay and it works. The biggest problem I have is being unable to locate any f*****g wiring diagrams. I have a chiltons manual and it is useless in this respect. I also want to test the coolant temp sensor but i don't know how.

If anybody can help me I would appreciate it very much.

I forgot to add that I've looked for a fuse under the dash but there dosen't seem to be one for the fan. All the fuses that are there are working so...

how high are your temps getting



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

I have this same problem. I've never been able to find an answer to it. I've ran through the whole cooling system, thermostat, etc. I finally just contributed it to a glitch with the computer not telling the fan to turn on and ended up shorting the relay so that the fan is on all the time.

The highest I've seen the temps go is just above half way to red. When the temp does start getting up there I can usually smell coolant but thats only while I'm sitting in traffic and as soon as I start moving the smell goes away and the temp drops dramatically. While driving I'm lucky if its gets above the starting mark.

Does anyone know how to test the coolant temp sensor? And does anyone know where I can find wiring diagrams for my car?

Check for a fusible link down where the battery cable connects to the starter motor. Fusible links are a piece of soft wire that acts just like a fuse. When too much current tries to pass through it burns open. Look for 2 wire ends around there. I had this happen on my '87 Sunbird. You should be able to get this at any good partrs store. However it's really tough trying to splice a chunk in. I just ran a new wire from the positive battery connection.





Blind Julius
<img src="http://registry.gmenthusiast.com/images/blindjulius/personal_pic.jpg" width=180 height=165>
"Oh! My My!" Splat . . . "Damn Squirrel ! ! !"

Thanks. I'll take a look and see if thats the problem.

Did you check the fuse under the hood. There is a black box on the drivers side (on 3 rd Gens anyways) which has fuses for large drain devices. Check it !

Your chiltons manual should tell you how to check your Coolant Temperature Sensor. My Haynes manual shows how and lists what ohms you should have on the multimeter when checking it.

I have the same problem, but I currently have the engine pulled so not addressing this (at the moment.)

There are posts on this subject in the j body forum. 1 post tells how to wire in a switch so you can cycle the fan in manually.

Another post I saw said something about this problem and said the solution was to change out the fan motor,. Something about it drawing too much and even frying out the switch he installed just cause the draw was too high.( after some time)

As far as the CTS , Chiltons usually says to pull the sensor and put in a pot of hot water and check the resistance in Ohms with a thermometer in the water. I don;t think a mechanic would do this cause they are usually a prick to get out without damaging so they would run it up to temperature and pull the connector and check it right on the engine.

I have a 95 manual and the ohms for the 2.2 are as follows:

All are in deg C

100 deg c --------177 Ohms
90--------------------241
80-------------------- 332
70--------------------- 467
60 --------------------- 667
50 ---------------------- 973
40 ---------------------- 1459

I think this is a good enough range for checking. to see if you have a "mis scaled" sensor.

And don't forget the most obvious!!. Check all your connections (sensor, to fan, at relay, etc.) Most times it's just a corroded connection!!.

Let me know how you make out

PS if you are running into trouble don't forget to turn your heat on high , defrost blower on high and open up the windows. This should keep you from getting too hot if your stuck in traffic.



Regards

I'm having a similar problem with my Girlfriends cavalier(2.2 99 auto) with the fan. It wont kick on when it gets hot or when you turn the a/c on. The fan motor still works when straight wired and the relay is still working as well. I have also hooked the car to a scan tool and I am able to make the fan come on with the scan tool. The coolant temperature read the same on the scan tool as the gauge in the car reads. I've also checked the wiring and it seems to be good. Anyone have any suggestions on what may be the problem?

seems like a comen problem, mine does the same thing with the not coming on with high temp or with the a/c.

i wired a switch off of the relay so if i do find the problem it should still come on. but i have control to turn it on if i need to.

hope someone finds an anwser cuz i would sure like to solve this one.

I've got the same issue with my 91. The fan works perfectly fine on its own, weve replaced the CTS, the relay we -think- everything goes to. Next step is to go short-hunting. If anyone has any wiring diagrams, I'd love to look at them.

Apparently, if the CTS is unplugged - the fan should turn on. If it doesnt, its (supposedly) a dead relay. Dont know how true this is.

Will update when I resolve it.

Another frustrated cavalier owner here: Same issue.

I believe we are all suffering from the same issue here, the easiest way is to turn the car on, and unplug the coolant temperature sensor.

after a couple seconds the fan will turn on; this saves time verifying the fan, relay, fuses, etc.

The ECU on these cars simply will not give the command for the fan to turn on, I don't know why.

I will update this if I figure it out, however if someone else has figured this out, your input would be greatly appreciated, because many MANY of us suffer from the same issue, and now that summer is upon us and it is getting very hot our cars are overheating.

Thanks