lumpydo

2006 A4 S-line with a 2.0 fsi. This morning it was about 40 outside. I got in the car and drove with the heater on auto and hi. Drove the car for about 20 minutes and the temp gague was showing normal temp but the heater was blowing cold. Any thoughts?

Audishiva

The Bentley Book of Audi lists four possible causes, all related to blocked or clogged hoses, heater core problems or defective ventilation control flaps. There is a fifth one not listed which is low coolant level in the system.

When was the last time you did any cooling system maintenance or repairs?

lumpydo

I just did the t-belt and waterpump a couple weeks ago. This was happening before that. I was told to check the core for clogs. I removed the 2 hoses and blew air through both the heater core (didn't seem to be a clog there) and the hoses.going into the core (also seemed to be clear). What it's doing is, when the car heats up, I can turn on the heat and it will blow hot. After a minute or two, it starts blowing cool. Like the coolant isn't going through the core very fast. But is still slowly going through.

chapstick

on a 2006 most likely the tstat malfunctioning and the coolant isn't getting to the heater core freely. You should watch the engine temp for erratic behavior.

lumpydo

The temperature gauge is normal. It lands right in the middle of the gauge and stays there. It's almost like the coolant goes through the heater core, but very slowly. Weird.

chapstick

I still think it's the tstat.

Could be a shot in the dark and your reservoir levels should be noticeable by now, did you purge the system of air properly after you did the tbelt and water pump?

lumpydo

Well, I'm not 100% sure I purged it properly. I don't know if there is a release valve or something. But I have kept an eye on the levels in the reserve tank. They did go down a bit and I topped it off. Since then the levels have been fine. I'll have to go.to you tube and see if there is a video on changing the t-stat.

chapstick

A few threads below I posted the air purge procedure that always works for me.

Check audiforums.com for the tstat swap thread.

lumpydo

Got it. Thanks. Checked it and its bled properly. Next, on the the stat.

On another note, I posted a question that no o e has answered yet. I have a torn front CV boot. Is there a way to replace that without having to replace the entire unit?

lumpydo

Ok it is having a heating problem. The car will heat up fine while I'm driving, but at idle it starts to cool.down. I was told the core.may be getting clogged with sediment and to remove the heater core hoses, rinse the core out, fill it with CLR for 10-15 minutes, rinse a couple times.and re attach the hoses. The system has been bled. But it still does it. I had the car running and listened the cap on the overflow tank up, and it seemed to work ok again for a few minutes at idle. Once the pressure but back up, it started again. The t-belt and water pump were replaced in September with brand new oem equipment.