tapndog01

Just recently converted to 134a. Now whenever I kick the turbo in heat comes blowing in through the vent with the A/C on. The seals are good and the actuators on each end of the blower housing work when there is a vacuum present. But what actually makes them close from the inside on the controls?

pnbell

So you're saying when you accelerate into Boost the Vents Blow Hot air?

Check the Heater Control Valve behind the intake manifold and above the bell-housing grounds. The seal gets worn and causes this issue... just fixed mine two weeks ago.

To check if it is functioning properly; Try sucking through the hose with your mouth, can you A) make if fully actuate? B) hold constant vacuum -does the valve change?

pnbell

the part is cheap, $20, and can be replaced quickly. You don't even have to replace the coolant valve if you just detach the arm.

porsche_addict

Check vacuum lines for the heater control valve. Also check the vacuum line that goes to the vacuum reservoir canister next to the battery. I had a similar problem with heat kicking in and the line to the canister was disconnected.