Hi fellow Audi masochists
Got a 2001 2.7bi-turbo allroad. At tickover speed heater blows cold or cooler yet above 2000rpm it blows hotter (but still not real hot)
Car had new stat before I bought it and engine temp gets up to normal nice and quick and stays there.
When I removed the hose which covers the bleed hole in the heater pipe hardly any coolant came out of heater. Expansion bottle is up to correct level and I've run it with cap off. Only way to get coolant to come out of bleed hole is unscrew exp bottle and raise it 6-8 inches. Did this, refitted hose as coolant poured out of bleed hole, topped up system but still same effect. Seems like heater has air blockage but how to displace it? I've worked in vehicle heating/cooling for over 30 years but this is baffling me. Read some old post on a forum that this could somehow relate to low vacuum pressure. I think there are issues with the car in this area (another job to sort) but how would this affect heater flow? Are there valves in the heater circuit that could block flow.
Sorry for long post but it's bloody freezing sitting at traffic lights just now!!
Jeff – in sub-zero Glasgow

 

Try flushing out the heater core. I see a lot of VW/Audi products with clogged heater cores.
Over here in the states we a have a product called CLR (Calcium Lime Rust) that i poor inside the heater core , let it sit for a few hours & blow it out with the garden hose.
Give that a try , top off coolant Take car for a good ride with the heat on high , double check fluid.
Your car might also have a auxiliary water pump in the back of the engine that helps circulation. Take a looky back there , make sure it is working.

 

Thanks - have flushed it once but worth doing again to eliminate it. If it was easy to get the matrix out I would just replace it but its a real pain.
From what I understand the auxiliary elec pump only kicks in at very high temps but the plumbing does concern me - it could effect coolant flow if some part of it went bad.
I think it's either air locked or it has something to do with the vacuum system / pipes. Will have another look this weekend.
thanks for input

 

Did you ever figure this out?

 

When you turn up the blower the heater core cools off and is insignificant. I have battled this problem but the cure is way to simple. I believe at some point my core was replaced before I bought it. Pull off the plastic in the cowling and swap the core hoses top to bottom. Heater blows hot as **** now! MERRY CHRISTMAS

 

I can't tell you how long this plagued me. Thanks for putting a solution on this question. I think it will help others with the same problem.

 

You're welcome and like I said. Merry Christmas