alanbl

'03 Allroad 6sp 140K miles.
Back in October, the heat quit. Took it into my trusted dealer and they replaced the climate control head. Said it was malfunctioning. Made sense since one of the ongoing symptoms for the past two years was that it always defaulted to celsius in the display, no matter what.

I was able to get some intermittent heat but not much. Also, they said that the compressor was always "on" unless I pressed the Economy button. It was a minor inconvenience so I could do this but still no heat.

They had it last week and found a loose clamp for the coolant reservoir that was leaking and air in the cooling system. This was fixed but still no heat.

As of today, it takes a long time for the oil temp to get up to warm but I still only get intermittent heat.

Has anyone had a similar experience and found a fix? Or, any suggestions on what next to check will be appreciated!

G0to60

Last winter I only had heat when the engine was above ~2000 rpm. This lead me to believe that the heater core was clogged and the water pump couldn't push enough coolant through the core at lower rpms.

Before this winter I did something about it and flushed out my heater core. Very easy to do even for a novice DIYer.

Materials:
~8' of 3/4" ID clear tubing
Twist type hose sprayer
Bucket
13mm socket (for battery)
Pliers (for coolant hoses)

First take off the shroud over the battery and rain tray. Below shows the material as well.



Next take off both of the heater core coolant hoses. Be sure that the engine is cold because a little will spill out (not much). I took out the battery to get more room.



Cut the tubing in half and attach one tube to each of the heater core points.



Next put one tubing end in a bucket and attach the hose to the other end.



Note: I've started the flush and you can see the color of the crud coming out.



Turn on the hose slowly and bring it up until you get a good flow. I did this for a couple minutes and then I switched the tubing so the flow would go the opposite direction. I did this a couple times until the water coming out was mostly clear.

Here's what was flushed out of the heater core.



Hook everything back up and run the car for a bit to get any air bubbles that may have gotten into the system. Then check your heat. From start to finish it took me about 30-40 minutes and now I have wonderful heat again. Even if this doesn't solve your problem it is a good idea just in case. Good luck.

alanbl

Thanks much for the heater core flush tip! I'll give this a try.

5v/cyl

If after you flush the core and get the air out with the proper procedure and still don't have good heat then reverse the hoses. Take the bottom heater core line and hook it to the top and top to bottom. This was the only thing that would fix my heat problem. Did it last winter and this winter the heat is still blowing hot.

alanbl

Good advice and I'll try it if the flush doesn't work. One question for you about your '03. Do you know if your compressor runs all the time unless you press the "ECON" button?

5v/cyl

It does run unless on "Econ" when outside temp is warmer. In the winter when temps are near or below freezing then it does not.

Barnstormer

It's normal operation that the compressor is "active" any time the econ button is not pressed. So, the CC brain decides when the compressor runs, both for cooling or for defrosting action.
Also, any time one of the defrost options is active, the compressor is on.

alanbl

Well, thanks everyone but flushing the heater core did not accomplish anything. No scale or crud came out and the water flushed clear.

It's down at the dealer and since I'm close needing the timing belt changed, I'm doing that and replacing the water pump and thermostat. Those are about the only things left short of replacing the heater core. Since that is not leaking, it seems unlikely to be the problem.

Stay tuned.

allroad23

Find a good Indy and bypass the dealer. It will save you a ton and if you build a solid relationship with your Indy then it will go a long way and you can trust him more than the dealer any day.

alanbl

Good advice, in general. But, I've been working with Stammler in Boulder since we bought our first Audi in 1998. They have been great to work with, accurate and although more expensive than an Indy have done great work and never soaked us. I'm a weenie gearhead in that I won't touch, other than basic stuff, either of our Audis but I do all the work on my RX7 and did everything including rebuilds of past cars including a '72 Vette and '69 GTO.