Fan Blower Motor or Blower Motor Controller Module

[martinz]

Is there a way to diagnose whether it is the fan blower motor that is faulty or it is the blower motor controller at fault when the heating / cooling fan doesn't work or works intermittently?

On my 2010 Audi A4 2.0, the fan works sometimes and doesn't work other times. Doesn't seem to be any pattern. Today it was very cold outside and it was not working so I opened the hood and took off the cowl and manually started the fan motor by poking it with a screwdriver. It would run but then stop. It wasn't like it just ran on the energy I provided. It would stop quickly as tho it was being forced to stop.

TIA

[mtroxel]

Usually, when the blower motor goes it's because the bearing is dry and seizes up. I had one, I could hit the dashboard up under the passgr side and it would start and run fine for a trip. Then we'd do it all again the next time. If the resister or control module is bad, it tends do just do squat. So from your description, I'd say that motor is shot.

[rcprato]

Usually if resistor is bad fan will only work on high speed

[mtroxel]

Usually if resistor is bad fan will only work on high speed

Good call. I've had that one too.

[Novarider]

Usually, when the blower motor goes it's because the bearing is dry and seizes up. I had one, I could hit the dashboard up under the passgr side and it would start and run fine for a trip. Then we'd do it all again the next time. If the resister or control module is bad, it tends do just do squat. So from your description, I'd say that motor is shot.

Along with this sometimes if you go around a big curve at speed you can hear the fan slow down. When you come out of the curve it speeds back up. I've had that happen twice over the years as well as having to smack the dash to get it going.

[Walletclan]

Good post.

My 2009 is in the same boat. The fan is intermittent and it seems to work more often when the weather is cooler. When it's hot, the fan doesn't seem to kick on until the car has been running for 15 minutes or so. It sucks.

[martinz]

I have ordered the blower motor controller resistor off Ebay. Will let you know if replacing it fixes it!

[martinz]

I replaced the blower motor resistor and the problem persisted. I purchased a new fan blower motor (Behr/Hella) from Rock Auto and problem solved. Interestingly, the old fan and new fan both seemed to spin similarly when I spun by hand - so I would say it was not a bearing but something else?

[Novarider]

Most likely the motor brushes wore down or broke. It happens in all electric motor at some point.

[Zingrox]

Most likely the motor brushes wore down or broke. It happens in all electric motor at some point.

Brushed motors yes

[Novarider]

Brushed motors yes

True, alltho brushless motors aren't all that common.

[Zingrox]

True, alltho brushless motors aren't all that common.

Also true

[Turbodan]

my fan is not working at all. I was about to order the fan and control module but when I scanned the obd 2 port, no faults were shown.
I have a Q5 that I replaced the fan and controller on last year but I think I saw the code first. it does not work regardless of fan speed or which setting it is on.
any ideas?

[Turbodan]

forgot to mention 2010 A4.

[Smac770]

You should have a DTC of some manner from the climate control module. "scanned the obd 2 port", no idea what that's saying. If it's not VCDS, OBDeleven, or Carista, it's up to you to know it can scan all modules. But if the tool has seen J255 DTCs in the past, then it still should now.

You could check the fuse that supplies power to the J126 controller which it uses to power the V2 motor. Right end of dash, center column (brown), fuse 8, 40A.

[Turbodan]

I used a bluetooth obd scanner which does not scan for hvac stuff. so it won't show up. so I ordered a new fan and controller. thanks anyway guys.