I have a 98 audi a6 and my heat nor my air conditioning heat or cool unless the gas is revving and or moving… the blower works…but no heat or cool… help
Some vehicles use vacuum motors to control the various flaps within the HVAC system. If your car has a vacuum leak the flaps won’t move correctly or stay in position. When you accelerate there is less vacuum, when you cost or idle at a light there is more, and the symptoms you describe could be caused by a vacuum leak.
If your Audi uses electric motors to move the flaps, then it’s not a vacuum leak.