Cooling fan will not shut off even when car is turned off and AC not blowing cold

MICHGRAD85

MEMBER
2002 VOLVO XC70
145,000 MILES

I think the problems may be related. My A/C stopped blowing cold although the drivers side was cooler than the passengers. Then I noticed the cooling fan running after the car was turned off for a few minutes. But now it will not turn off at all. I disconnected the battery and when I reconnected it the cooling system will not turn on at all but the fan still will not shut off. I am thinking there may be a problem with a sensor and I was hoping to not have to replace the whole fan assembly. Any ideas?

2 Replies

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

The fan assembly will be ok. The sensor is separate and usually not too expensive. The worst thing it could be is a PCU called a Fan Mode Control Unit. This works with parameters from the ECU, Engine temp, A/C, Oil temp and a few other things. It is also in control of turning off the cooling fan within a certain amount of time after the car is turned off.
Get a trouble code reading at a dealership or service station and it will come back with the failure code for the part causing the issue.
I hope this helps and let me know how it turns out.

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Saturday, September 17th, 2011 AT 5:14 PM

JIS001

MECHANIC
3,411 POSTS

I had a question for you? Did you mean the cooling fan as in the radiator fan? Or the blower motor inside the vehicle? For the A/C not cooling, the symptom you explained by one side being cooler then the other indiscates you are low on freon. Most likely from a leaking A/C condensor. If your blower motor is what is staying running then the transistor has failed. Good luck to you ahd keep us posted please.

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Saturday, September 17th, 2011 AT 11:15 PM