Mike Simard

My 928 seems to always use outside air in all(?) HVAC positions. Even the owners manual says to select Off if driving through odors. My wife wishes there were an option to use only recirculated air and it is annoying that the car is always using outside air. If you were plowing through a field of flowers that might be ok but in reality any air outside the car while you're driving is going to be nasty and in the case of Atlanta like hooking up a hose to a trash incineration oven, throwing in some pollen, opossums and roadwork materials and blasting the results into your car. I do feel that I have a faulty recirculation actuator problem because there's always outside air coming in even when switched off but even if I fix that there will still be a desire for true recirc air free of outside air.
My question is should I consider modifying the operation of the recirc flap while I'm tearing into it for the repair? Would it be nice to have the recirc flap closed to outside air under anything other than say maybe the foot level selected?
Aslo just what HVAC settings are supposed to shut off outside air in normal operation? I would guess AC on would but the owners manual implies that only switching it off would close off outside air.

WallyP

Pages 87-106 thru 87-109 show the flap position program, and how to test it.

The flap is closed (which gives fresh air) when there is no vacuum on the actuator.

It would be possible to install a single-pole double-throw switch in the circuit to the vacuum solenoid that operates the actuator.

If the switch completes the existing circuit, you would have standard operation (recirculate on DEFROST and at max A/C cooling, fresh air the rest of the time).

If the switch is flipped to apply ignition-switched voltage to the solenoid, you could close the fresh air inlet and have recirculation.

You would hook the wire to the solenoid to the center terminal of the switch, the wire from the control head that did go to the solenoid to one side, and ignition-switched power to the other side.

killav

I have this same problem. If laying on your back, in the passenger side footwell, and looking straight up under the dash, their is an oval "flap" that never opens. I turn the A/C head from max cool to defrost to heat. This door never opens. Is this the fresh air flap? If it never moves, is this why I constantly have hot or cold outside air????

SeanR

here ya go

http://members.rennlist.com/pirtle/svc_act.html

Doing same thing a few threads down.

Mike Simard

Also helpful for the recirc actuator is: http://members.rennlist.com/v1uhoh/air.htm

Thanks for your post too Sean, you're really hardcore into your HVAC

Wally, thanks for the info! I do like the idea of a seperate forced recirc switch, now to figure out a seamless oem stlye way of incorporating one....