I started to notice this yesterday that my car was blowing cold air when it was sitting still. I paid more attention to it on my way to work today and every time I stopped (stop sign/light, traffic, etc) the car started blowing cold air.

Anyone have any suggestions on where to start? I just replaced the coolant temp sensor this summer.

Fan not working and not pulling air when car stops? Clog?

Thanks.

 

air in the system?

 

I notice the same problem with my A6 -- it just does not seem to blow really hot air. I usually set it to 69-72o and leave it on auto. I have experimented and if I crank the temperature to HIGH, it then blows hot air but the car gets too hot. If setting it to HIGH does not work, then it could be air pocket in heater, bad valve, blockage, etc in heating system or even vents not opening. Love the OOOO, but sometimes I long for the days of a simple on-off heater.

 

no heat at idle is a huge issue with the v6 and usually aflicts the 2.8 i have had this issue for 6 years on my audi 90. thought it would have pushed out an air pocet by now. i even replced the core.

 

Ne heat at idle is usually a thermostat problem. However, it could also be some sort of engineering problem with the pump not pushing enough water through the core. Is your coolant temp reading in the middle? If not, start there and change your t-stat. Try a 195 degree t-stat if you can get one. If that doesn't work, try blocking off part of the radiator with cardboard. If your coolant temperature is OK, try putting a small electric pump in the inlet heater hose to boost the amount of water going to the core.

 

Its possible that when th ecar is sitting, the slow running pump can't overcome the air lock in the heater core you might have. I suggest bleeding the cooling system to be sure. Thsi car has two bleeds, one on the main coolant hose and one on the heater hose next to the battery. The heater hose one is often forgotten becaue you have to pull back a fabric jacket on the hose and unclip the hose and pull it back to expose the bleed hole.

 

Not to thread jack as I have the same issue but some facts that may be worth mentioning as stated above I have the same isue with my V-6 . I have had the issue for 6 years now so you can see this is not an overnigt issue.

it had the issue when I firs bougth the car and since it needed atiming belt i redid the pump and stat at the same time . I have since replaced the stat again with no help . What is unusual is tha it blows scorching hot in my driveway if I rev it and the engine at 90C . i take my foot off the gas , then engine stays at 90C but the heater blows freezing within about 10 seconds . I can take it out on the highway and the temp will show 80 C due to the air over the engine but it still blows scorching hot .. hit stop and go traffic though on the highway at -10C and your doomed ...
So i tore the whole dashboard out and replaced the core ... bled it to death and still have the exact same issue . Wouldn't an air pocket work it's way out after about 6 seasons ? I get only streams of coolant when I open the bleeder . p put the front of the car on jack stands est , open all bleeders and still nothing .
I even put in mentioned pump and just had luke warm heat constantly after that. So i put things back and under extreme pressure from the wife bought her anothe Audi for winter . At least that one blows hot at idle ... and I even changed the t belt stat and pump on that one and bled it the same way ( another V6 )