'90 Audi 90 - No heater valve?

There are two hoses. Supply and return. On T44s the control valve is a white plastic part with a vacuum line to it, located just behind the engine's head.

The plastic ones break so it may have been replaced with a steel one.

T> Does anyone know if my Audi 90 should have a heater valve? I can't see that

Thanks Tony,

I know what the T44's heater valve looks like. I've had experience with one failing. As far as I know the 90's heater valve should be identical.

I'm looking for the heater valve on my Audi 90 model. So far I can't find it, strange as it seems. I've followed the supply hose from the thermostat flange to the firewall. No heater valve. I've looked up what the heater valve for the 90 is supposed to look like and evidently its supposed to be the same one as the T44's. The car is not producing much heat to the cabin so that has been my inspiration to investigate the heater valve status. Maybe that it was removed at one time and never replaced? The car was originally located in San Antonio TX so heat would not have been a big concern. Where SHOULD these be located in the 90 model?

TIA, Steve

I called a friend who is an independent mechanic for audis.

He said that the 90s had, in some cases moved the heater control valve back into the heater box with the coil. Rather fun to get at.

The B5 chassis (later) went with an always-on system where the heat was controlled entirely by the air flaps.

His guess is that it is more likely that the heater control flaps are the source of your problem. If you are familiar with the T44s the complex vacuum system for flap control is a source of many hours of mechanical challenge. If your system is vacuum operated you should check for leaks or inoperative vacuum relays.

T> Thanks Tony,

Thanks for all of your help Tony, I was afraid of that :(

Steve