Chris Franks

thought one German car wasn't enough so I just bought a 98 A8, what a cool car!

However...the heat and the A/C are non-existent.

All the controls seem to work great, but both heater core hoses going into the firewall don't get hot, even before that auxiliary pump thing. The car operating temp is normal.
Also when you set temp to low, no change in temp either, it always just blows ambient temp air.

Any ideas?

nyrobbie77

i'm dealing with a no heat issue in my 97 A8 as well. i'm not sure where you are located, but most a/c systems do not engage the compresser at lower temps, usually below 35 degrees.

as for the heat, you may have an air pocket in the system. where the hoses go thru the firewall there are two bleeder screws. once the engine is hot and running, open them to let the air out. you should have some coolant come out too.

also check your radiator hoses. my lower radiator hose was always cold. i changed the thermostat with an oem and now both get hot as they should.

currently, my lower heater hose is warm, upper is cold w/no coolant flow. i believe that the lower is the inlet, upper is the outlet to the cores. am thinking i either have a plugged heater core or the valves in my after run pump are stuck closed.

after checking all that, scan the HVAC system with vag com scan tool to see if you have any codes for faulty flap door motors.

hope this helps and make sure to update us with your solution.

Chris Franks

I'm in Seattle, it's a nice 50 degrees today.

These bleeder screws you're referring to, they are between the aux pump and the firewall? Mine has what looks like a set of radiator flush couplings right before the aux pump, but I'm pretty sure it's not OEM.

I don't have VAG COM, but I have the dash all ripped apart and can eyeball the flaps all moving. My heater cores are obviously cold.

I will go check the radiator hoses, would have thought that if I had a faulty thermostat, the car would overheat... and does not explain my lack of AC also.

nyrobbie77

the bleeder screws are on the engine side right at the firewall. they've got a slot in the center for a screw driver or ribbed edge to put pliers on to turn them. its possible that someone along the line has changed them out.

mine did not over heat either with the stuck thermostat. the tstat does have a small bypass valve that allows some coolant to flow at all times, perhaps thats why.

the heater cores should half coolant flowing thru them no matter the flap positions, so theres probably a flow problem, either the aux pump is stuck closed or a clogged heater core.

good luck and keep us posted