Hello my S40's fans don't seem to be running properly. The white fan on passenger side doesnt come on at all and black fan on driver side comes on a high speed when car starts to overheat. I can drive with heat on without overheating. I changed thermostat, ECT from a used S40, and I also found a black wire that is coming out from switch on top of white fan I followed it all the way to under the air filter area where I.found that it wasnt connected. I figured this must be ground wire so I grounded to negative side of battery but still no fans. Please help! any suggestions greatly appreciated!

Thanks,
Ari

 

When you turn on the air conditioning does the fan immediately run at high speed?

 

No not right away only when car begins to run too hot.

 

There are 2 fans up front. I believe the black one is the fan for the cooling system only. The white one starts running (in addition to the black) when your a/c is switched on. Which one is working in your case?


Have you checked the fuses? If the fuses are good then I'd next check the relays.

 

Looks like neither fan is on when A/C is switched on. The black fan for cooling fan comes on high when its overheating. How would I go about checking the relays and which ones should I change?

Thanks!

Ari