JohnelP

I have no heat in the car. First checked the heater hoses from the engine compartment and they both have same temperature (so I belive the coolant flows normally ???)

So I thought it is the temp regular flap motor. After dismantling last night the dash board to reach the flap (though realized only glovebox area needed removed... learning forever.... ) the actuator motor seems to work, and if I manually move the red actuator to move the flap, it provides a slight difference in air flow volume and the difference from cold to very cold . AC (cold during summer) works OK.

I got lost.... what can it be now?

myers1.8TQ

Try searching next time, its easier and get faster results.

Search for "no heat" and you get plenty of results to read through<ul><li><a href="http://search.audiworld.com/search.html">this helps</a></li></ul>

myers1.8TQ

. . . or heater core is blocked.

JohnelP

Engine warms up normally. Tstat was changed last year with genuine one. If the heater core is blocked, the return hose from heater should be cold, right? But it is warm. As warm to hold as the incoming hose. Are there any other flaps? Can it be the actual flap controled by temp motor to be broken, and the red hinge to witHout effect?

dorsal900

Not sure what year your car is, which might make a difference as the system evolved over time. On my 1996, there are four electrically operated flap solenoid motors and one vacuum operated flap. The "red" arm solenoid operates the flap that diverts air between the floor vents and the defroster - it does not control the temperature.

Based on what you wrote, it seems that the thermostat is allowing the coolant to heat up and that the heater core is not plugged - these are both very good signs. Unfortunately, there is another control solenoid that seems to have a high failure rate on older cars; it has a "natural" (ivory) colored arm, and is the one that controls the temperature mix - it fails because it operates continually, making small adjustments as you drive.

If you have a VAG Tool, the best thing that you could do is run a scan in the HVAC system which will tell you whether the control unit thinks that there is a problem. If not, you need to take a look at the "natural" solenoid and see what it does when you change the temperature from "low" to "hi" - you might be able to see it with the glovebox door open, or you might have to take the glovebox off. Oh, it's on the passenger side of the heater box, close to the firewall.

If you decide that you need to replace that solenoid motor, note that I used a shortcut - see the next FAQ down the list. I was also able to successfully repair my solenoid motor as well as a spare if you are interested and it will fit your car.<ul><li><a href="https://forums.audiworld.com/a4/msgs/2827215.phtml">Temperature regulator flap solenoid fix in the FAQs</a></li></ul>

alchu

I have the same issue. tstat was replaced today (that fixed my issue of the engine not getting hot), both hoses get hot, still no heat in cabin. air flows fine... I was about to check next steps. It's not the heater core, it's no longer the tstat - mechanic is sure it has something to do with the center console... he suggests I bring it to the dealer at this point.

Vag - no issues in HVAC.

myers1.8TQ

"suggests I bring it to the dealer" = $$$

dorsal900

After the car is warmed up (the clever control unit does not blow the fan until the coolant is hot, may not move the flap either?), turn the car off. With key in the "ON" position (engine off, warning lights on), try changing the temperature control from whatever you have it set to "HI", wait a bit, then change it back to "LO", then repeat. Listen carefully under the glove box - you should hear the motor whirring and moving the flap. If you do not hear this, somethng electrical is not occuring, whether in the control unit or the motor. Based on my experience and that of other posters, and the fact that electromechanical parts wear or gum up, I would guess that the temp flap servo motor is the problem.

Does your mechanic have a VAG tool? Did he scan the HVAC controller for codes? A normal OBD-II tool can not access this controller, but the freeware version of the VAG Tool can read and reset the HVAC codes.

alchu

So to recap:

t-stat changed
both heater core lines are warm
I have a vag, no hvac codes
with engine hot but off, changing from lo to hi I hear a clicking noise and presumably the flap opening and closing.

at a loss here! a dealer will charge me who knows what to fix this...

alchu

and I don't need to listen by the glovebox - the clicking flap noise is loud enough to hear from driver's seat.

Appreciate all the help guys...