Any idea on my 97 A4, I Have no heat… If the car gets up to operating temp and I have RPMS up to 3-4 grand heat slowly starts to come up after it idles
The heat goes away.

 

Have you done anything recently on the car? Changed coolant, or filled it up?

Could be air in the heater core or blocked neater core.

Check the hoses in the engine compartment going to and from the heater core at the firewall.

 

I fludhed out the heater core and i am getting flow in eiter direction. I used the outlet hose to bleed the system and i did not seem to have any air. I am thinking the t-sata may be stuck open but then when the car gets hot i should have heat all of the time.. I dont know....

 

If you have access to a VAGcom see if you have any codes in the HVAC system