Another shot at the no heat at idle problem

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Aug 14, 2013 | 05:18 PM

#11

jseklund

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Prospeeder - also, have you seen the auxiliary pump causing these issues? Maybe mine is bad and not pumping and I don't know it?

Aug 14, 2013 | 06:44 PM

#12

Prospeeder

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From: Washington

well the auxiliary pump does run all the time and assists in moving coolant through the block, so its something to at least inspect that its buzzing and running while the engines hot. i cant say iv replaced a non functioning aux pump, just leaking ones.

Aug 30, 2013 | 04:08 PM

#13

ajg617

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Quote:

Originally Posted by Airbag

Because soemtimes the core is NOT bad. I replaced mine and the problem continued. But if everything was fine, you did your timing belt or water pump and now you have no heat you have trapped an air bubble.

To the OP a little bit better is not fixed . mine always felt like id fixed it in the summer , but as soon as November hit i new it wasnt fixed.

I had the same problem on my 03 A6 Avant 3.0. Cold air at idle which go progressively worse until I got cold air at speed. Took it to the local Audi dealer. They told me that the fresh air flap was stuck in the open position. Don't want to tell you what that cost to replace. After it was done, I was back to warm air at speed and cold air at idle. Finally took it to my indy (where I should have gone first). He uses professional grade HVAC cleaner from the local HVAC supply (sorry I don't know what he uses but I can probably find out). Flushed the core with that, filled it, let it sit overnight and all the next day. Picked it up in the evening and I had wonderful heat yet again.

Aug 31, 2013 | 04:34 AM

#14

jseklund

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Thanks for the replay. I am going to have to wait until winter to see how well it is fixed, but it appears that I have warm air at idle. My gf's A4 had a much worse version of this issue, no heat at all, even under speed, and I feared that I would have to replace the heater core on that one. I still may....but after leaving CLR in the core overnight, flushing it, leaving CLR in the core again, and flushing about 100-150 gallons of water through it (some in both directions), I got an giant amount of crud out of the core and she now says her heat is very hot. We will see if it sticks.

On my car, my heat is warm at idle, but I'm not sure yet if it is 100% solved...I just have a bad feeling about it all.

On a good note, the cores are much less expensive than I thought - it is just a bunch of labor to put them in, so I'd like to avoid it all...

Sep 4, 2013 | 04:44 PM

#15

Airbag

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From: In my Garage

been there .. there is not a more depressing feeling than going through replaceing core .. and having the same problemsem ..

Sep 5, 2013 | 09:06 PM

#16

meternerd

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Well, just my opinion, but I'm still guessing air in the system. Bleeding is a major pain, but pulling back the heater hose and letting air escape FINALLY had mine working just dandy. But every time I thought I had all of the air out, I'd get a few more "burps". Did it after a timing belt change. I won't even get into what a treat THAT is!

Sep 6, 2013 | 02:42 AM

#17

4Driver4

Tech Guru

Joined: Oct 2002

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Quote:

Originally Posted by meternerd

Well, just my opinion, but I'm still guessing air in the system.

Agreed.

Sep 6, 2013 | 11:22 AM

#18

Prospeeder

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Joined: Aug 2011

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From: Washington

Can somebody please explain how magically air could still possibly be in the system. I have done a hundred timing belts and water pumps and other countless cooling system repairs and yet to ever have air like this. Its a quick drive, burp, top off done. You guys are nuts if you think air gets trapped that bad in these systems, especially since the thermostat has a air bleed hole. Its clearly a clogged up core, nice that people are having luck with CLR and other chemical soaks, might have to try that.

Last edited by Prospeeder; Sep 6, 2013 at 11:36 AM.

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Nov 25, 2013 | 06:40 PM

#19

ajg617

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Joined: Jan 2006

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Quote:

Originally Posted by Prospeeder

Well, I have to say it worked for 2 years. But this morning at 12 degrees, marginal heat and a nice gurgling sound coming from the dash the whole trip to work. I think you are probably correct - may have gotten some of the junk out of the core 2 years ago, but not everything. I'll probably try it again though since winter seems to be starting early. Wish it would just hold on for another winter since timing belt is due and would have to empty the system anyway. At least the heated seat helps!