Rear heater blower runs only at full speed even if is turned off

[florin83]

I have a Multivan 2008 and suddenly the fan from the rear started to run at maximum speed. The controls on the dashboard or on the rear top panel do not work even though I turn it off, it keep going at full speed. The only solution to stop the fan is to unplug the connection to the rear motor.

I have changed the rear blower motor resistor but the problem is still present. It runs at full speed even the unit it’s on OFF position.
After an VCDS scan I have these errors:
the first one I don’t think that have to do with my problem.


Another aspect that I noticed is that during the operation of the rear air conditioner, the button of the central air vents always flashes. It can be seen in the attached film.

New video by Florin T

photos.app.goo.gl

What do you think could be the problem?

 

[florin83]

Any suggestions?

 

[Loz]

The fault suggests a wiring issue or similar to the rear sensor. Try unplugging the sensor itself.

 

[florin83]

Do you know where is located?

 

[Loz]

If the fault code still exists (doesn't change) then you need to check the wires for chafing..

 

[florin83]

Thanks, i will check.

 

[florin83]

i changed that sensor but the problem is still present

The central vent switch light flashes and as you can see this actuator is moving by itself.

New video by Florin T

photos.app.goo.gl

 

[MarcisB]

Did you try to remove the rear top panel and look at the connector there?

 

[florin83]

In the meantime, I opened the back panel to access the climate control unit. All plugs are ok and have 12-14V.

I still think that there is a problem with a part that controls those rear components because they are different problems: rear blower that works at maximum speed even if the climate is off, the motor that directs the air between the feet and the ceiling moves by itself continuously (see previous post), the motor from the ceiling can be also heared working non-stop. I tried to remove the plugs from all the motors one by one, but there is no change, the others still have the same problem. That's why I said that the problem is somewhere in the front, from a part/module (it's there a relay/module that controls the rear climate?), because there was no way that all the components could have problems at the same time.

I tried to change the back ceiling control panel with one from a friend who has a T5.1, but it doesn't work even though they have the same code. After I installed the T5.1 one, the related fuse blew, the same thing happened with mine installed on T5.1, so they are not compatible.

 

[florin83]

Offtopic: is there a way to remove the ceiling climate panel without breaking the clamps?

 

[MarcisB]

You mean these metal f**g things?
May count is 1 broken and 2 bent out of 4 on the 1st try. Took one from lamp pod.
They get stuck and bent behind the control panels plastic edge.



If I would do 2nd time I would pull out the panel straight down from both edges without wiggling side to side so the clamps don't get caught deeper behind the plastic edges. The sides of main panel are pretty elastic so you can put some plastic stuff in there and try to get the gap as big as possible.
I think I will also cut some plastic off the straight plastic edge as 3 out of 4 clamps are bent now in two places
I will also lubricate with silicone when I install the control panel back.

 

[DeividasM]

Hello,
First of all - sorry for bad English, i am writing from Lithuania
Today i had 100% identical problem as yours. Rear motor works full speed all the time, and one of flaps ooerates also. Į had to desconnect the. But center vent light on climate control doest flash on mine.
Have you found where was the problem? Cheers

 

[florin83]

Hi, sorry for late reply.
I haven't done anything to the car since then, but it needs to be fixed because the weather has warmed up and it's not pleasant without air conditioning in the back.

Now I'm trying to get a rear control panel to test it because from what I understand it's the "brain" of the rear climate control.

 

[florin83]

if you solve the problem in the meantime, please reply here

 

[mr_waxdope_noodle]

I have the same problem in my California, any solutions? Thanks

 

[roadtripper]

Offtopic: is there a way to remove the ceiling climate panel without breaking the clamps?

If you get 4 thin flat metal blades, like a classic butter knife, you can slide them into the gaps where the clips are and that will release all 4 clips.

Luckily I had a second hand one to look at and figure the clips out out of the van...

 

[florin83]

Sorry, I forgot to post. I’ve managed to fix the problem.
The circuit board of my rear control panel was corroded.
A good electrician was able to fix it and now is working.