Rad cooling fan not working

BIGJOHNKNC

MEMBER
1999 CHEVROLET CAVALIER
200,000 MILES

2.2 engine. Have checked all the usual suspects, fuse, relay, ect. As well as checked for voltage to the connector. No power to the connector going into the fan. Not even when ac is turned on. It did read 0.02 volts for a sec. Should there be voltage to the connector? And if there is supposed to be voltage to the connector then I know I have a wiring prob right? Just trying to see if there is anything else I can check before trying to dive into the wiring.

1 Reply

SQM

MECHANIC
6,383 POSTS

Hello,

First, have you checked to see if the fan is operational? You can provide 12V power to the fan to see if comes on.
Also note that the fan will have power to the connector when it gets the signal from the ECM.
The coolant temperature sensor provides that signal to the ECM. If the coolant temperature sensor is faulty it will not send the signal to start the fan.

Here are couple of helpful articles:

https://www.2carpros.com/articles/how-a-coolant-temperature-sensor-works
https://www.2carpros.com/articles/symptoms-of-a-bad-coolant-temperature-sensor

I have attached the diagrams for the temperature sensor as well as the wiring schematics for your reference.

Please let me know of any questions.
Thank you.

Images (Click to make bigger)