Gidday Everyone.

I'm slowly putting some KM's on my 1.8t Mk2 and have noticed some quirks with the Heat and Ventilation system.

Does anyone have any experience with vacuum controlled heater systems in a Turbo Mk2 application? Iv noticed some quirks that could be related to Boost rather than Vacuum!

What iv noticed is that the valves all come to life when I start the car, the vacuum system controls all the vents and what not. But when I start driving things happen... are they normal? Who knows.


Firstly, there is a click when I roll on the throttle. Like there is a vacuum switch in my heater core? Behind the switch matrix? Am I going mad?

And secondly, when I have the fan on while stationary, it blows air. But as I accelerate, I hear a valve move in the heater core and the airflow changes. About 60kmh, then it opens again as I decelerate...

Feature or fault?

Some background of the car, I pulled the heater box out, removed the foam and Aluminium taped the valve paddles. Removed the coozed Aircon Evaporator. And reinstalled with no AC. (A really awful job). There is a teeny tiny one way valve on the line to the system (the factory one)

Cheers,
Tim

you might need to put a one way valve on the vacuum feed. Would be easy to try.