IcemanG17

everyone is right.....this is the default no vacuum modes for most 928's that only have the 1 center comb flap

1: recric flap is open for fresh air only
2: footwell flap is closed, so no footwell airflow
3: center comb flap is closed (down) so air is diverted more to the side vents from the center
4: defrost vent is open
5: heater valve is open (hot all the time)

changing airflow on the control won't change anything.....all you can do is adjust temp and AC a bit until vacuum is restored....

IcemanG17

this sounds VERY familiar.....when I 1st got my 928 I had a typical zero vacuum problem.... so I started at the source and replaced broken things along the way.... In the summer I used the zip-tie fix to keep my heater valve closed....but in fall when I cut the zip tie (after vacuum was fixed) guess what....it would NOT open....so I went from no vacuum all heat, to always on vacuum no heat WTF?!?!? the problem was the solenoid on the strip behind the stereo that controls the heater valve died...& when those solenoids die the default mode is to allow vacuum, hence the not heat all the time!!

Just buy a used one from 928 intl for around $25....I think I posted a thread on it...I'll see if I can find it

here it is
https://rennlist.com/forums/928-foru...r-problem.html

I never posted an answer, so I just did today...take a look

jenyap

That makes sense except mine is intermitent. I wonder if a failing vacuum solenoid could cause this condition.