Troubleshooting No Heat Issue on 2011 A3 8P?

[jk83]

I am currently not getting any hot air when I have the heat turned on. There may be a very slight lukewarm air when the blower is set to the lowest setting but it quickly cools when I turn the blower up. I am not getting any codes on my code reader. I flushed the heater matrix once with warm water but still no heat. The in and out pipes from the heater matrix are both hot.

I have been researching and think it may be the heater control valve that is broken but I cannot seem to figure out where the piece is located? Is it possible the matrix is still clogged even with both in an output pipes being the same temperature? Otherwise the car is working fine, no over heating, no leaking anywhere, no codes.

I have attached a pic of the part I am concerned with.

Thank you!

[evo v]

Do you have any heat coming out when you direct the air to defrost, legs only etc.? On mine one of the motors that drives the flaps was seized. There are 4 or 5 of them under the dash.

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[red4life5]

Almost positive it’s still the heater core. Common issue with our cars if the coolant is regularly changed. Did you try back flushing it with some pressure?


2[emoji4]1[emoji4] A4 S-Line Prestige

[yeoldbluebird]

feel the upper heater hose and the lower. if the lower hose is colder than the upper its a flow issue indicating the heater core is clogged. I had to backflush mine a couple times. The only time I had any success was when I used BG cooling system cleaner and pulled the hoses while they were still really hot.

[evo v]

Just in time for the winter now I'm experiencing similar issue. I have very low heat coming from left vent and cold air from all other dashboard vents. I need to check the hoses as was suggested above.

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[evo v]

Sooo... I did a little troubleshooting today. Checked upper and lower hose. They are both hot. I checked the sensors in the vents - both side vents and foot vent... all are reading good. Started checking the motors and found the bottom driver side locked up. I free up the sensor and the warm screw inside the motor. Still no movement when I plug it in. I picked up used motor from the local junk yard and the motor and the flap started moving. I ran the car up to temp - still very little warm air coming from any vent. I revved it up to 4K RPM and warm air started coming from the foot vent. Dropped the RPM to 1K and the air went back to neutral temperature. I am not sure what can be the issue. Any suggestions are welcome. In meantime I will be running it in sports mode on high revs

[evo v]

Little progress on the no heat issue. I thought last night what did I do right before I started experiencing this issue and was there anything unusual. So I replaced the turbo 2-3 weeks ago along with the downpipe. When I removed one of the coolant lines no coolant came out at all but I thought that it was due to disconnecting the turbo coolant line. So I disconnected the hose from the same spot - the bottom hose on the left of the oil filter and again was bone dry. I traced the coolant and it goes from the expansion tank to the auxiliary water pump on front of the engine. Then goes back up to the hose I disconnected and to the turbo coolant inlet. It is between the turbo and the block. I filled the hose on the turbo side and quickly connected it to the metal section. Now I have heat in the car even at low RPM however is not as strong as I remember. So I think that axillary pump is defective and not circulating enough coolant to the turbo. Basically the coolant is driven by the main water pump. I will replace the aux water pump and hopefully this will resolve the issue for good. Part # 1K0965561J.