S40 Cooling Fan Runs - Drains Battery

tomphillips · Post by **tomphillips** » 04 Mar 2013, 09:17

2000 S40... Car can sit overnight and if I start and run for just one minute and turn off cooling fan will continue to run draining battery. What should I look for and where should I look? TIA.

Tom.

Post by **regent** » 04 Mar 2013, 12:30

With the fan running, pull out the Fan Control Relay (if you have one) to rule out a sticky contact. The ECT Sensor is another thing to look at (it may trick the computer into thinking the engine is hot when it is not) but you should see an incorrect temp gauge behavior in this case. Do you?

On certain older models, there used to be a 2-pin thermal sensor on the radiator that controls the fan directly (in series). See if it is stuck closed.
On other models, there is a Solid State Relay located on the fan shroud (it may fail shorted and fan runs forever).

Sorry for the general info - I no longer have access to the electrical schematics that we used earlier in the forums to pinpoint exactly what you should look at.

tomphillips · Post by **tomphillips** » 04 Mar 2013, 14:09

Thanks for your reply... found the locations from earlier posts. We'll check them both. Thanks again.

mr midnight · Post by **mr midnight** » 21 Mar 2013, 01:11

check the sensor located in the thermostat housing, same thing happened to me and the sensor was the problem.