ltooz_a6_a8_q7

Hello all,
This morning was 56F and when I turned on the heater (HI setting), no heat came out all day. AC worked, what could it be? The controller? I tried full defrost, only AC, no heat. Inputs please...

Thanks,

E-Town

It stops the coolant from flowing through the heater core.

austinado16

If you have VAG-Com pull the codes for the climate control and see if a code for the flap motor comes up. You can also do an output test mode and make everything work via VAG-Com.

Start with the simple diagnostics first.

Remove the plastic tray in front of the wipers. You'll find the vacuum actuated valve on the driver's side of the heater box. Fire up the engine and let the coolant get hot. You should have both heater hoses hot as well.

If the one going through the valve is hot and the bottom heater hose isn't, you know either the valve is closed, or the heater core is plugged.

If both hoses are hot, you know you have a hot heater core, and therefore, the problem is the blend flap that allows hot air to mix with the cold air coming through the heater box. It's not uncommon for the motors to quit working and it is possible to take them apart and clean them up inside and get them functional again. New ones are $85ea online.

ltooz_a6_a8_q7

Thanks guys, I'll debug it tomorrow....

Pr0ph3t

I had the same problem a couple of years ago. The motor that actuates the heater box door was fried. Search the FAQ for the procedure to replace it. The part was about $65 from autohausaz.com - it took about 90 minutes to install and test.

ltooz_a6_a8_q7

about the heater, tons of pictures, but none tells me what a blend flap looks like. Can you show me the picture or how to get to the flap. Looks like I have to write up how to again on this problem.

Thanks,

austinado16

With the plastic tray removed from in front of the wipers, you can see several of the lingage arms and flap motors.

There is one flap motor in the big round duct that connects the A/C evaporator to the heater box. Note the squarish box on top of the round duct. That controls a round door inside that looks like a throttle plate. You can move the rubber boot back a bit and watch it work.
<img src="http://pictureposter.audiworld.com/57225/evaporator_resized.jpg">

There is also a flap motor inside a box there above the vacuum actuated heater valve. Unscrew the cover of the housing and then you can watch it work. (sorry, I don't have a photo of it)

On the passenger side of the heater box there is some linkage you can watch working.
<img src="http://pictureposter.audiworld.com/57225/heater_box_resized.jpg">

In the next picture I've labeled where I think the heater flap is and if you look on the plastic housing, you can see the arc molded into the housing where the flap swings. When the flap is up, it makes the air from the blower go downward, through the heater core (who's tall rectangular outline you can see vertically there at the bottom middle of the heater box) and then into the car. When the flap is down, air is blocked from going downward through the heater core, and so just old air comes into the car. Of course this flap can be in any position as the climate control computer "blends" cold air from outside with some air going through the heater core to provide whatever tempurature you've asked for.
<img src="http://pictureposter.audiworld.com/57225/heater_box_heater_flap_diagram.jpg">

Anyway, point being that I think the flap motor you're after is the one located in the box next to the vacuum actuated heater valve. As such, it should be real easy to pop out, clean up and get working.

This is where VAG-Com and the "output diagnostic test mode" comes in handy because you can actuate each of these motors and then stand there and watch them work (or not).

The climate control unit can do a self diagnostic and show you it's own fault codes. I think there's a page on how to do this on 12v.org or similar.

ltooz_a6_a8_q7

Thanks Todd... I'll try it

ltooz_a6_a8_q7

Hello all,
Since I had no heat and it's cold, I didn't have time to open it up to check the flap valves, I turned off the AC controller, and this morning, I turned it back on, turn on and the heat came out.... HOT... I checked all the vents and they all have heat. I think it's may be the electrical connection. I'll check the connections this weekend.

Thanks all for your help, it's a great forum,

Cheers,

austinado16

To make it move all the flaps into all the different combinations. Just to get everything moving and working.

I don't driver ours that often because it's the wife's, but when I do, I try to remember to make it do all the functions it can do...one thing at a time. I'm hoping that will keep the flap motors happy.