Mercedes: MERCEDES C280, mercedes c280, vacuum servo

Question
I HAVE A 94 MERCEDES C280 AND THE CENTER VENTS BLOW COLD BUT THE TWO OUTER VENTS BLOW HOT LIKE AS IF THE HEATER WERE ON WHAT COULD THIS BE?

Answer
Jason,
The climate control has complex interaction between components. You may have a bad fuse on the system, or a bad vacuum control servo. Or the mono valve that controls water flow and direction may be sticking. Or not operating at all if you have a vacuum hose off or a bad leak.
If the system is in defrost position for instance, then the ac run to dry out the air before it goes over the heater core.
If the system is calling for blended air, you may have a defective vacuum servo under the dash. Or you may have a vacuum leak under the hood.
I would begin by checking the  fuse box for burned fuses. Then I would begin looking for a cracked vacuum hose. With age, the rubber becomes stressed and brittle. If a vacuum leak occurs anywhere on the system then there is not enough suction to allow the control units to remain engaged during AC operation.

You will need to check each hose separately.

Good Luck
Rob