Ac/heat blower fan not working, randomly turns on and off

you will start at the blower motor itself, hotwire it with power and ground, if that works then work your way backwards in the system, the blower resister is usually next in line and a big problem on many cars. Looking for burned connectors, broken resisters and then tapping on the main control unit and wiggle the wires connected to it may find the problem, if your blower is intermittant, it probably is not a bad fuse but could be a weak connection, a volt meter will do a lot of the troubleshooting for you once you get access to the connectors, lots of information on youtube.

Audi Q7 2008

Hello everyone,

Just wanted to share my experience with the intermittent running blower. Cutting out. Starts and stops itself.

if your blower is working but keeps cutting out then there are more chances of a faulty blower. I have experienced this with a Q7 fan blower. As the brushes can’t be changed EASILY, this is the best solution in my views.

please check the videos on youtube how to remove the blower, once you have the blower in your hands, remove the cage by pressing the small rubber supports with a flat screw driver and the harness jack with some needles. You need two needles or strong pins which you need to insert in the jack from sides of the pins. Once its out, file the brushes touching the armature and you are good to go for another one or two years. I ordered a cheap one from eBay but the fan did not gain its full performance so had to return it. Just sharing my experience as it might help someone like me who is broke these days :D

Hi:

Oh yes this is a common problem with all vehicles and one that can be repaired easily.

First off some background info to get you in the right mode. The speed control chooses the speed of the motor by changing the resistance in series with the DC fan motor. These resistors are all attached to one board with shovel plug attachments and the whole assembly is stuck in the air vent to keel them cool. The motor drives the air to cook its own resistors. The wiring to this unit has the connections housed in a plastic plug matching the connections on the board. Now where is this resistor board in your car. Well it is directly on the other side of your glove compartment shelf. You can pull the drawer down by carefully dislodging the stop clips found at the upper edge of the drawer on either side. Squeeze the top sides in a bit to allow the compartment to swing out and down to reveal the wiring behind. Now the resistor board part is fastened to the air vent with two Philips screws. Unplug the wire connector carefully using a small flat blade screw driver to move out the latch type arms holding the plug into the resistor board. Then remove the two screws and pull out the resistors.

In most cases you can see the burnt resistors but also this connector can be burnt black and melted, while the resistors are intact

To solve your problem you can purchase either the resistors , the plug harness or both. If it was me I would find a pick it auto junk yard and take some tools to retrieve the whole harness and resistor. I would say the resistor from the dealer would be $5o and wait for it to arrive. The wiring repair plug and harness probably another $50. Pick your used part probably $10.

Oh yes, take the old part with you so you can match the parts. You will find this fits other year Honda cars so have a look before passing a possible vehicle. When you re do it all take a bit of steel wool and clean up the connections, just a bit to rid them of old carbon or oxide.

Have fun

Alton

Don't know if you got your problem fixed - it's an old post but here's what we did. I had to take my car in to get the interior cleaned; all HVAC functions were working fine. Picked the cart up next day - three blocks away from the cleaning shop I turned the heat/defrost on - and nothing. Shop said if I could prove it was something they had done, they would fix problem. As in prove that somehow they shorted something out - as if.

After a month without a car (too cold outside to work on it) and much online searching, testing of fuses, resistors etc etc a Honda mechanic my grandson knew suggested to him that it most likely was the whole heating unit that was blown. New part 700.00 - no return if this wasn't the problem. Grandson went to wreckers - bought a part for 20.00 - problem solved. He found a manual and instructions online.

Part Number 52409 Temperature Climate Control Knob Assembly: 20.00 at wreckers

Check the connector from the blower motor to the harness behind the glove box.