Cooling fan will not shut off

Mark27 · Post by **Mark27** » 01 Apr 2013, 13:35

I recently installed a new coolant thermostat (I accidentally broke the plastic nipple on the existing thermostat while changing the timing belt). Cooling fan acted accordingly for a few days. Then out of nowhere, I drove the car to work (about 25 miles) and the fan does not turn off after I get out and enter the work place-draining the battery DEAD

Does anyone know what may be wrong- keeping in mind I just purchased a new thermostat/sensor from Volvo?

Mark27 · Post by **Mark27** » 01 Apr 2013, 13:36

I forgot to add 03 S80 T6

Post by **regent** » 01 Apr 2013, 15:02

Fan CTRL relay contact is most probably 'sticky' - take it out to confirm.

Update: I see that most P2 cars actually have a cooling fan CTRL electronic module (rather than a simple relay) - see item 4/71 on the diagram: http://www.volvowiringdiagrams.com/volv ... agrams.pdf

Most often it is the ECT sensor (the one in the T-stat housing) that fails and then the fan runs non-stop because the computer thinks the car is always hot; from your initial post it looks like you will be replacing the right component. Did you also have any problems with cold start?

It may also be possible (but less likely) to have a failed shorted cooling fan control module that would keep the fan powered regardless of the input from the ECT.