Need good explanation of air recirculating malfunction

[spugeddy]

Hello all,

I am new to 944 ownership, and have spent the last two weeks trying to understand and fix several issues my car has. I have looked on this and other forums, but am struggling to know exactly how to tackle this.

One I need to lock down pretty quick-like is that air from outside is always flowing in even with the fan to 0. Even when moving the sliders left right or centered. My AC doesn't blow cold but that is a different issue. I want to lock down the air recirculating issue. I would like to close it off to outside air and even disconnect it from opening to keep it on recirculating air only. Can someone give me a quick and dirty how and where and what to do.

I have already been in the fresh air squirrel cage area for non working wipers, so is that where to start, or under the passenger dash board area. My heat doesn't work either, but I am in FL and don't need that to work right now.

car is 86 NA 944

[spugeddy]

I read some more and it seems the airflow is on whenever the ignition is on. I'll open the squirrel cage and see if the flaps are opening and closing when pushing the recirculating

[kdjones2000]

All of those flaps are driven by your engine vacuum.

There are 2 very difficult to find nipples on the firewall behind the block near the exhaust that should be connected to your vacuum plumbing.

There is also a vacuum reservoir near the battery that is part of the setup.

Make sure that all of these are connected properly, and then you can start looking inside for actuators working correctly, HVAC control panel providing the correct voltages to the actuators, etc.

https://944online.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/v/a/vacuumcontroldiagram.png

[944 Ecology]

If you close your recirculating flap permanently, you will end up with foggy windows, unless your AC compressor is turned on.

Probably a better idea to make it work the way it was designed to work.

[djnolan]

The vacuum is supplied off of the break booster. Make sure the one way valve in the line is in the correct direction. (easiest fix ever if it is backwards!)

[spugeddy]

Ok. Great. Thanks. I'll start tracking down vacuum connections and check valve

[spugeddy]

didn't see any major vacuum line issues, except this which is directly under the #4 exhaust. and the check valve off the brake booster seems to be right direction...right

[djnolan]

That one goes to the evap system. Here is a diagram of the HVAC vacuum lines setup...