To sum it all up, there is one of two possiblities. 1, you have a vacuum leak (under the battery, red hose)
2, the potentiometer for the blend door is not reading.

------------------
Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM