Hot air only works on passenger side?

[MBHGB]

Hi Guys. So I have a 2005 Audi A4 B7 Avant 1.9 TDI. Basically I am only getting heat out of the passengers side and not the drivers side even when its on high temperature.

Does anyone know the fix for this or is this a common issue? Thought I should get this fixed with the weather now getting much colder.

Thanks in advance!

[arman123]

most likely your HVAC motors playing up scan it with vcds see if any faults

[pdlh]

yes, it's a common issue as the cars get older. As Arman123 suggested, you need to get a fault scan of your car done, or look at the error log of the 08-Auto HVAC settings on your car.

In simple terms, your A/C is controlled by 5 stepper motors, which move position to control the different vents on your car. Each of these motors has a coloured bar so you can identify the motor. On a Right hand drive car:

• XXX Control motor for temperature regulating flap right yellow V 158 8E2 820 511

• XXX Control motor for temperature regulating flap left red V 159 8E2 820 511 A

• XXX Positioning motor for defroster flap green V 107 8E2 820 511 B

• XXX Actuator motor, footwell flap / foot well flap black V 70 8E2 820 511 C

• XXX Positioning motor for recirculated air operation blue V 113 8E2 820 511 D

Green, Blue, Red and Black are easy to access and replace by removing the glove box, but lucky for you the yellow one on the drivers side is a complete pig. I did it last weekend so I can confirm this is a pig.

You need to buy a replacement, when I last asked these were £153 + VAT from Trade Part Supplies so likely more from Audi direct, so not cheap. Often the motor can be removed and opened up carefully. I've found my motors still work fine (and can be tested with a fly lead and a PP3 9v battery), but within the motor is a variable resistor, which is a small white disc of plastic with copper plates inside with a couple of electrical connections. It's the copper plates inside this disc which wear away over time, which then gives false read outs to the A/C controller about the motor position, this in turn causes the motors to go beyond their limits and stall. Some have had luck removing this plastic dial, cleaning it with a cotton bud and electrical contact cleaner, but it's not really easy and for me this only worked for a week before the motor jammed again. Mine always jammed in the Ice cold position which seemed to be on the drivers feet.

Ultimately, a replacement was required and I turned to eBay. There is lots of choice, between £15 - £50 but ultimately, they have all been removed from similar age cars to our own, so it's a bit of a gamble. I chose to buy from this eBay seller, (no connection) but only because he offered a short guarantee on the part.

Control motor for temperature regulating flap 8E2820511 - Audi A4 B6 B7 WARRANTY | eBay

Now for installation.

1. Open the drivers door,
2. Using a flat screw driver, or the car key, remove the fuse cover at the end of the dashboard.
3. Using an 8mm socket, remove the 3 screws which secure the lower trim panel above the drivers pedals, it then pulls down and forward from just under the dash board trims
4. Carefully remove the diagnostic connector from this trim panel. There are a couple of push clips and it slides out.
5. (If you have an auto car, this part is easier) if not good luck. you have to reach up and find the stepper motor with the yellow connecting bar, this is held in place by 3 x 6mm screws, again remove with a small socket.
6. when the motor is loose, you can remove the power connector and then rotate the motor to release the keyed yellow connecting bar

repalce is the reverse.

Once done, you really need to use VCDS to calibrate the replacement stepper motor.

1. To do this you go into 08-Auto HVAC menu option
2. If I recall correct, you go into 04-Basic Settings
3. Select Group 1,
4. The stepper motors will all move to their limits and self calibrate. (takes about 60 seconds)
5. Checking the error log, you should no longer have any errors.


Now three other bits of advice.

1. I've done this twice this year. On both occassions I dropped one of the tiny screws which held in the stepper motor. The first time was a nightmare, and took about 3 hours to find the screw which had dropped down behind the drivers foot rest and then went under the carpet! Magnetic tools could be a good thing.
2. I found it helpfull to also remove the black pipe cover to the left of the pedals (held by 2 small screws with a 6mm socket) which covers the coolant pipes from the engine bay. It gave a little more access for my hands.
3. make sure you put the motor back in the same way as you removed it, it's easy to make the connecting bar (yellow) be in a slightly different arc of movement.

Good luck

Paul

P.S. If that does not solve your issue, you likely have a blockage or air lock in the coolant system, but much less likely as you have heat on the passenger side.