I am working on a 2.2 cavalier 97andthecooling fan wont turn on. Realy and fuse are good. I ran a power wire to the fan and it works so thhe ground is good. I even cleaned it on the back and front of the tranny. I tried unpluggine the coolant sensor and it still doesnt come on. Even with the ac on nothing. Idle the ompressor turns on and off every few seconds with the AC on. The Relay never clicks to tun the fan on.




On the inside my car looks like a fighter jet.

Anyone?




On the inside my car looks like a fighter jet.

At the sender:

Check for 5 volts at the yellow signal wire first, if no power you have a bad feed wire or an ecm issue. If you have 5 volts, jumper the two wires going to the temp sensor at the plug, the temp at the ECM should go above 130 celsius on your scan tool. If it does, you have a temp sender problem. If it doesn't, and you have 5 volts on the yellow wire, you have a ground problem. Ground the yellow power wire to chassis ground, the ecm data should show the coolant temp at 130 celsius or higher, confirming the ground issue.

Edit: If you do NOT have a scan tool that will show you the cars ecm data stream in real time, here is a simple way to do this. If you have 5 volts at the yellow power wire to the temp sensor, when you jumper the plug, wait a second and you should here the cooling fan relay on the drivers fender click. This is because the ecm sees the full voltage and thinks the car is overheated, if this works you have a sensor problem. If you do not hear the click, ground the yellow wire to the alternator housing or a good chassis ground, and you should hear the click. Same thing, the ecm thinks you have overheated and tells the fans to come on, this method would be a ground wire problem.