Periodically, my vent fan will not turn off. Yes, I understand the engine fan often stays on for ten plus minutes. However, this is the vent fan. And, no matter what the fan is set on, it always goes to the max setting. I have a brand new battery and it is strong enough to keep it going and several times I have caught it after an hour - even two. I suspect sooner or later it will run the battery down. Volvo had no idea what that problem was and, no kidding, wanted a thousand bucks to trace the problem (labor intensive). I'll take my chance on the battery and some rain in the windows before I outlay that kind of cash. Any help would be appreciated.

 

That's actually a normal situation. After the car shuts down, the cabin blower comes on for a while to dry out the evaporator so that it doesn't get moldy and smell.

I am guessing that it comes on 30 or 40 minutes after shutdown and runs for a while.

 

Sounds like it could be the blower motor resistor which controls the fan speed. I've read where sometimes when it is going out the, fan will continue to run even after the car is shut off. The fan only running at one speed make me suspect the resistor.It's located under the glove box in the blower assembly.

 

Guys, I can't believe I didn't reply. Thank you for your insights. It must have found out I wrote the forum because it only comes on for a few minutes now. Thank you for your help!