Mark'sA8L

that mounts under the hood next to the ac/heater assembly?

A club member with a 99 A8 was told he needs one.

It is restricting the flow of coolant to the heater cores, and the heater will not blow warm at all.

PaulW

Due to noise they make.....never had it effect heating performance.

I would say that it might be a control valve that is also right there, or the wrong coolant or inadequate coolant or not properly "burped" system.

Mark'sA8L

and is still not working correctly after. The temp gauge in the dash is reading normal. I know we put more coolant back in the car then what we drained out. It also did not have the correct coolant in it when we drained it.

If coolant is properly flowing through the system, both hoses at the firewall should be warm correct?

PaulW

Did you open the vent valves on the two lines and bleed them with the car running? Just crack them and the water pump pressure will force coolant out.

Make sure the HVAC is in HI when doing this and that the car is warmed up.

I highly doubt it's the pump you reference.

If the wrong coolant was in the car....then it can foul the heat transfer surface....that could also be the problem.

Mark'sA8L

and bleed it so he could double check it after we did the timing belt. he said he has driven for a week now, and checked and was not uable to get anymore air out of the system.

I do not have a paid version of vag-com so am unable to get into the climate control system to check for errors and to see which,how many of the actuators are messed up.

But this car will only blow extremely cold air all the time regardless of what temp you have it on.

If you have it on a cooler lower temp it all functions correctly, even regulating the fan speed.

But nothing works correctly on warmer/higher temps.

RustyKelsea420

Just wanted to pop my head in here and give a big thanks to you Mark for all this. By the way, how much would a full version of Vag-Com cost me? And also, all functions work correctly no matter what temp it's set up. Fan speed, upper, lower, and defrost vents, etc. The only thing that does not work is warm air. No matter what, it's cold. Like it's actually running the a/c. The car even drips condensated water when running on full blast in Hi temp, like it does in the summer with the a/c cranked up. We WILL get to the bottom of this! ~ Rusty

simmerling

I have same problem .Seems like coolant return valve stuck.Anyway customer tels me to replace all this waterpump valve unit.