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Mike Kelly
Mike Kelly, Audi Mechanic
Category: Audi
Satisfied Customers: 5469
Experience:  17 years experience as a auto mechanic, foreign and domestic.5 years running my own repair business.
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Audi Allroad Quattro: I have a 2001 Allroad, the heater sometimes

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I have a 2001 Allroad, the heater sometimes wont blow hot air. Sometimes it will. The car engine gets to correct temp within minutes of start up so its not the thermostat. When the heater does blow hot it works great so I dont think its a heater core block or air block. Is there a control valve or similar that can jam or intermittently fail??

Hello, welcome. My name isXXXXX will do my very best to
assist you with your question.

Do you hear any kind of noise coming from the dash clicking,etc?
Customer: replied 3 years ago.

Hi Mike,


When I adjust the temp setting (on auto) from a hot to cold or vise versa I can hear a small clicking from the dash. This clicks about once a second. The fan also increases speed up and down depending on the temp setting, its around 10 deg C outside here so the fan slows right down when a low setting is entered and blows flat out at a high setting..



Ok the issue that you are describing is the mode door actuator inside of the dash that opens and closes the flap in the air/heat box.The actuator is a small electrical motor and in your case the motor is electrically failing and sticking.To correct the issue the motor needs to be replaced.
Customer: replied 3 years ago.

Is there one motor for both sides or 2 separate motors?

For the temperature there is only one.
Customer: replied 3 years ago.

Thanks very much, i will check this out!! Where would I locate the motor?

The dash will need to be pulled out as it sits inside near the ac/heater box.This is a very labor involved job,thank you.
Customer: replied 3 years ago.

Hi Mike,


Only the glove box needed to be removed so I have checked out the flap motors, one is to change where air is directed to and the other moves when the temp is adjusted up and down. Both of the motors seem to be moving freely and the mechanisms look to be going to their full extents in both directions. Do you have any other ideas??

You should not be hearing the click noise I know the motor is turning are you sure the box itself is moving. Sometimes the piece in the box can break and not move anything when the actuator is anything.
Customer: replied 3 years ago.

Hi Mike,


I have disconnected the motor and can manually shift the levers, it feels like like a flap or door is opening and closing. There is a small amount of resistance through out the motion and it seems to close into place.


Today I will try and flush/bleed the system. I did not think that this is the problem but I am running short on ideas.

Ok,this does sound like the motor and air box is ok.Flush the system including the heater core and let me know if there is a change,also is the check engine light coming on?
Customer: replied 3 years ago.

The check light does not come on, the dash displays OK after startup. I will do the flush etc later today.....

Ok sounds good.
Customer: replied 3 years ago.

Hi Mike,


I have flushed the system and there was no sediment or contaminants, just clean coolant followed by clean water. I have bleed the system again and still same symptoms.


There seems to be very little water flow coming to the heater core, after trying everything I think this is the problem although I cant figure out why there would be a lack of flow. Someone has suggested to try an fit an auxiliary pump before the core to see if this increases the flow into the heater. If this works it would be fixing the symptom rather than the initial problem so its not the ideal solution but worth a try....


Do you have any other ideas???






This really sounds like a possible water pump failure,this sounds like the water pump is not spinning fast enough to give the coolant system a fast enough flow.
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