engine sometimes overheats and you turn ac on it cools?

Question

My 2001 pontiac sometimes overheats and when it does I click the ac or defrost on and the fans click on and cools the engine. I was told it could be the ecm. What do you think?

Answer 1

I think you've got a bad fan relay switch.

The fan relay switch takes the signal from the ecm and turns on the fans.

It's highly likely that a simple relay switch is broken and stuck in the open position. A fan relay switch typically costs less than $20.

Answer 2

Try a thermo fan switch first, sounds like the ECM isn't getting the signal to activate the fan