2014 Q5 3.0T - no heat?

**weirdinside** · 01-12-2019 04:02 PM

A friend of mine's Q5 has an issue with the HVAC - When it comes on it seems to blow slightly warm, but then when he cranks it to high, it only blows cold air.

the PCV valve, thermostat housing and water pump were all replaced recently, and the engine warms up to temp properly and doesn't run cold or hot. What could be the issue?

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**turbophreak** · 01-12-2019 04:23 PM

Blend air door or actuator maybe? What does it do when you do the same low to high temperature setting with the A/C on and in recirculation mode?

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**djn876** · 01-12-2019 06:05 PM

Possible it wasn't bled properly/completely after the coolant refill. I would think this would result in engine coolant temps being off as well, but could be a bubble stuck somewhere. If there were no issues with heat before the work was done, most likely related to the work performed. There are additional steps even if a vacuum fill was performed. See below for excerpt from manual following a vacuum fill. Obviously keep the reservoir sufficiently full the whole time.

1. Bleed at SC screws, one at a time (passenger side first).
2. Bleed heater core hose (passenger side, just behind positive terminal in engine bay, need to remove plenum cover)
3. Manual refers to a parking heater, not sure what that is, but turn it on if it has one.
4. Lastly, perform the following:
– Tighten the cap on the coolant reservoir until it locks into place.
– Start the engine.
– Set the temperature to “HI” for all zones and set the fan speed (0).
– Press the AC button to turn off the A/C compressor (LED OFF).
– Run the engine at 2000 RPM for 3 minutes.
– Run the engine at idle until both large coolant hoses on the radiator are warm.
– Run the engine at 2000 RPM for 2 minutes.
– Turn off engine and allow it to cool off.

**weirdinside** · 01-13-2019 07:26 AM

Originally Posted by djn876

Possible it wasn't bled properly/completely after the coolant refill. I would think this would result in engine coolant temps being off as well, but could be a bubble stuck somewhere. If there were no issues with heat before the work was done, most likely related to the work performed. There are additional steps even if a vacuum fill was performed. See below for excerpt from manual following a vacuum fill. Obviously keep the reservoir sufficiently full the whole time.

1. Bleed at SC screws, one at a time (passenger side first).
2. Bleed heater core hose (passenger side, just behind positive terminal in engine bay, need to remove plenum cover)
3. Manual refers to a parking heater, not sure what that is, but turn it on if it has one.
4. Lastly, perform the following:
– Tighten the cap on the coolant reservoir until it locks into place.
– Start the engine.
– Set the temperature to “HI” for all zones and set the fan speed (0).
– Press the AC button to turn off the A/C compressor (LED OFF).
– Run the engine at 2000 RPM for 3 minutes.
– Run the engine at idle until both large coolant hoses on the radiator are warm.
– Run the engine at 2000 RPM for 2 minutes.
– Turn off engine and allow it to cool off.

Thank you! The issue was present prior to the car having work done, which is why the work was done haha. You are probably right about the flush being done improperly and causing an air bubble somewhere, I'll check with him and see what he says!

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**djn876** · 01-13-2019 08:26 AM

No problem, this is at least easy to check, otherwise probably blend door or control module. Could also scan with VAGCOM and see if any codes come up

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**weirdinside** · 01-13-2019 10:30 AM

not sure if this would help diagnose, but a new development: if he turns the fan speed all the way up, it only affects the rear vents, and it seems that the heat gets colder after the car is fully warmed up - while the car is warming up, the heat comes on fairly lukewarm. when he turns recirc and a/c on and off, mechanical feedback is heard but nothing cabin wise changes

**xnikita83x** · 01-14-2019 11:34 AM

Hey, I'm the guy he sold the car to lol. So I spoken to the shop, and they said the next step is to replace the Auxiliary coolant pump. Can someone confirm? Also, is it the one the is the one near the firewall connected to the the coolant lines going into the firewall to the heater core?

**xnikita83x** · 01-14-2019 11:42 AM

Actually I think I founded it. I think. Driver's side below the reservoir

**A U D I** · 01-14-2019 03:03 PM

Originally Posted by xnikita83x

Actually I think I founded it. I think. Driver's side below the reservoir

Hi, it is going to be your auxiliary coolant pump as the problem. Contact your closest Audi dealership to see if it is covered under the recall

**xnikita83x** · 01-14-2019 03:35 PM

Originally Posted by A U D I

Hi, it is going to be your auxiliary coolant pump as the problem. Contact your closest Audi dealership to see if it is covered under the recall

I did not know there was a recall out for it

**xnikita83x** · 01-14-2019 03:46 PM

Just looked it up on Audi's website. No recalls for my VIN. So to replace it, can I just take off the passenger wheel well liner to get to it or do I need to take the bumper off? Anyone know?

**xnikita83x** · 01-15-2019 07:16 AM

Originally Posted by xnikita83x

I did not know there was a recall out for it

Do you by chance chance know if I can get to the pump from the wheels well by taking out the liner or do I need to take the bumper off?

**djn876** · 01-15-2019 09:14 AM

Taking the liner out is the way to go, bumper off doesn't really help just because of where it is. It's a pain either way because there's just not much space. If you replace, you'll need to bleed the system again since you are going to lose a bunch of coolant doing that job.

Not sure why that would keep you from having heat though? That pump is just used for the supercharger coolant loop and other than sharing the reservoir it doesnt communicate with the main loop and therefore heater system at all.

The recall was for an Aux HEATER, which also wouldn't be your issue since I don't think that's in play at all once the engine is at temperature.

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**A U D I** · 01-15-2019 10:10 AM

A failing or failed auxiliary pump will cause a restriction of the coolant flow to the heater core

**xnikita83x** · 01-15-2019 01:14 PM

The shop that worked, which is a very reputable German car speed shop, confirmed also that that is the next thing to replace. My new issue now is that the cheapest I'm finding this pump for is online for 400-500. Dealer wants nearly 700. Every other 3.0t vehicle has this pump for 200$ or less including the q7. I don't understand why this is the only one that's so damn experiencive. Do you guys know if one sourcedbfrom another 3.0T engine will work?

- - - Updated - - -

*Worked on the my car before*

**PNW Avant** · 01-15-2019 01:23 PM

Whats the part number?

**xnikita83x** · 01-15-2019 01:25 PM

8k0-965-569-a

**SQive** · 01-15-2019 02:35 PM

Originally Posted by xnikita83x

Every other 3.0t vehicle has this pump for 200$ or less including the q7. I don't understand why this is the only one that's so damn experiencive.

Because it's the one you need.

**xnikita83x** · 01-15-2019 03:09 PM

Well, I usually have been lucky, this being my third German car. My wife's A3 has 78k on it and all that has gone bad was the sensor inside the radiator, and I'm not worried about it. My mk6 GTI only issue is in had to replace the radiator round 55k miles(110$). I'm still hoping I find one of these pumps at a cheaper price, or if someone know s if a compatible one.

**A U D I** · 01-15-2019 03:40 PM

That pump is just for the supercharger.

**xnikita83x** · 01-15-2019 04:12 PM

Right, but like you said before, wouldn't it still restrict flow to the heater core? Cause at idle is when I have the main issue, mainly after the car has warmed up fully. I'll drive around for a while with the heat coming sufficiently, not blowing out as strong as I'd expect at full blast and not HOT when on hi but warm enough to be comfortable. But soon as I slow down and park, it will go to straight cold.

**djn876** · 01-15-2019 07:48 PM

That pump should not impact the flow through the heater core. There are a few diagrams of the coolant system out there and the two sides don't really talk to one another except for sharing the reservoir. I personally don't see how that could impact the heat, but maybe I am missing something.

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**A U D I** · 01-17-2019 06:44 AM

FS: CWA100-3 Upgraded coolant pump w/ harness $300 shipped
https://www.audizine.com/forum/showthread.php?t=842030

**xnikita83x** · 01-19-2019 03:25 PM

Well I just replaced the Auxiliary coolant pump that sits behind the engine and no change. Gonna try and flush the heater core next see if there's a blockage. Had the shop do the pump since I have no garage where I'm at ATM. After they did that then they recommended I try to see if the core is clogged. Wish they would've checked that first. O well, u live n learn.