Darien

Doing the annual AC stuff and noticed that my comb flap doesn't move.

I've searched but couldn't find a detailed break down on what position it should be in for warm air or cold air. It currently stays the same position regardless if the engine is running.

Pics with illustration would help so I'll know what position mine is stuck in

the flyin' scotsman

The comb flap is a mixer of sorts.

I personally believe its way over engingeered so I deleted the flap and one of the potential HVAC vacuum issues.

When Tony configs his system to summer mode I believe the CC is essentially WFO.

Darien

Here's the current state.

Seems like I've read a few posts where folks just capped the orange tube that goes to the actuator. Will that change the position and air temp?

IcemanG17

Darien
That is the standard NO vacuum position, when vacuum is applied it moves up to allow greater airflow through the main center vent.....so when the comb is down it diverts more air to the side-footwell-defrost vents... After reviewing the "maps" in WSM that show when the comb flap is open-closed it appears it is open during MAX a/c and closed for pretty much everything else...

Mine is in the down position all the time and I still get plenty of cold air out of the main vent & side vents.....so it appears it doesn't do much...so I left it alone

Darien

Thanks Brian

I found Tony's write-up on a summer modification (below) and I'm leaning toward doing it. I'm planning on driving over to Dallas this summer and will need all the cold air I can stand

http://members.rennlist.com/v1uhoh/summer.htm

jthwan22

That is when I go bald and comb my hair flap over the bald spot.

Manfred

Check out Dwayne's post on HVAC R&R: https://rennlist.com/forums/928-foru...re-w-pics.html

Sounds like you have a bad actuator diaphragm for the comb flap (orange vacuum line). You certainly can delete it's function and do fine but if you follow Dwayne's post it's not a bad repair. You can replace just the diaphragm of the actuator (get the diaphragm from Roger at 928sRUS). I just finished the job on mine--took about 1hr to get to the actuator and another 20minutes or so get the diaphragm in and reconnect the lever arm (I was lucky--I can imagine that reconnecting the lever arm might take more time).

Bill Ball

That actually makes more sense than anything Porsche has written about the comb flap.

dr bob

Just listening and feeling around in different modes, my amateur analysis has the comb flap in default/closed position in heater or defrost modes. Rest of the time (AC or vent with cool temp slider position) comb flap is in actuated/open position. Running with the AC on and the failed comb flap in default/closed position reduced center vent airflow to less than half, so it's worth fixing IMHO. Failed comb diaphragm bleeds air into the system, causing other actuators to also go to default positions, so heater valve is open, defrost is open. Not good if you arevtrying to cool the car off.

Pull the head unit and do the clutch relay fix. The rest of the console R&R isn't that tough. Replace the diaphram for that, and consider the recirc actuator at the same time. All your console R&R effort will be needed again when you do the defrost vent. Clean and inspect the setting motor while it's all there in front of you with the pod out.