'01 v70 a/c fan stays on

SandCastle · Post by **SandCastle** » Mon Sep 11, 2017 7:07 pm

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, 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.

Post by **abscate** » Mon Sep 11, 2017 7:17 pm

I understand the issue is with the fan inside the car, not the radiator fan

The control unit (sometimes incorrectly named ECC) turns the fan on after running to keep the evaporator dry. It sounds like that function is Fubar. That's the officially Volvo for Novemver Foxtrot Uniform.

Probably good diagnosis since moving the fan control to OFF isn't solving the problem.

Tone944 · Post by **Tone944** » Tue Sep 12, 2017 3:51 am

I used VIDA/DICE to turn the "dehumidify" feature off. Just makes me nervous having a fan running full speed consuming battery power when the engine isn't running! I'm sure it has caused me to need my wife to rescue me from a carpark once. All it takes is a battery that isn't quite up to the task and this feature can tip it over the edge.

Sandcastle's issue sounds like there could be a relay sticking or failed power control circuit somewhere. I'm not sure where you would find that one though...

Post by **abscate** » Tue Sep 12, 2017 5:04 am

You could try a control unit swap from an old car or eBay unit. They rarely go bad

SandCastle · Post by **SandCastle** » Sat Oct 07, 2017 4:19 pm

I purchased a used Climate Control Unit; it did not address the issue - the fan continued to blow full speed.
I pulled the CCU and the fan continued to blow. This pointed me to fan regulator; bought one from Amazon, along with a new fan. Figured if I was going in, might as well get both. Replaced the fan and regulator (previous notes about that right-rear screw being impossible are correct). Appears that we are back on the road!
Thanks to all for suggestions.
Donald C.