'01 v70 t5 a/c blower fan stays on

[SandCastle]

Hello, 2001 V70 t5; 220k miles. The past several months the a/c fan works sometimes and not sometimes. When it is not blowing I still feel cold air in the vent, just no fan. Other times everything works fine. Vegas odds are 2-1 that it will not work on any given drive.
Yesterday I noticed the a/c fan was blowing when I walked by the car. I know this happens from time to time so I was not concerned. Well, guess what? Last night the battery was totally drained; I guess the fan never stopped. Today I charged the battery and took it out for a test drive. No a/c fan, which was not unexpected. About 7 minutes into the drive, the fan came on and I continued on for another 5 minutes home. Turned the car off and the a/c fan keeps blowing. Waited anxiously about 5 minutes and the fan is still blowing (seems to be almost on high). Started it back up, hit every a/c related button - fan on constant. Not wanting to drain the battery again, I pulled the negative cable.
I have little mechanical know-how, but I follow directions well and have a pretty good local mechanic. I fear the Volvo dealer $$$$
We would like to get another year or so out of this car; any suggestions are appreciated.

p.s. I mistakenly posted this to the earlier model v70 forum, apologies for that ...

[chrism]

Not sure if you're talking about the cooling fan behind the radiator or the blower fan inside the car. If it's the cooling fan, then the problem is likely the fan controller which is mounted right on the fan assembly along with the fan motor. A good junk yard may have one.

[SandCastle]

Not the radiator fan. Definitely the blower fan inside the car. Does this sound like the a/c control unit on the dash? Guess the best way to get the right part number is to pull it; then look for a used unit.

[93SCMax]

Two suggestions:
1) Buy some canned air, the kind you use to blow dust off your computer/keyboard. There is a small opening on the ac control panel. Behind the opening is a temperature sensor. Take the canned air and blow off the sensor. Over the years, they collect dust and crude and can affect the reading and hence the blower speed. Clean it and it may help, especially if it has never been done before.
2) If that doesn't help your situation. I'd remove the blower motor and check the fan blades for dirt/crude build up. Even if you change your cabin air filter regularly, build up on the blades can occur. I had a similar problem with mine, removed the blower, cleaned the blades and reinstalled. Been working great ever since. It's not easy removing the blower, but if you have patience and some basic tools and skills, it can be done.

Don't be alarmed about the blower motor running with the engine off. This is normal. You can do a search and find lots of people have had your unwarranted concern.

The drained battery is another issue. I believe it is separate from your blower issue. How old is the battery? Is it OEM?

Good luck.