hello all...

the heater/defroster switches on our '87 300d are not functioning properly.

no matter which switch i depress, only the DEFROSTER is working...there is no airflow thru the heater vents in front or rear.

i assume this is some sort of vacuum problem??..could someone steer me in the right direction as to exactly WHERE the vacuum lines are for the heater controls??

please don't tell me the dash has to come out...

If you remove the glovebox, you will find a manifold with multiple small plastic hoses running to and from it. IIRC the green one supplies vacuum which is distributed to the pods controlling the flaps, directing the distribution of air. Each of the pods can be tested by applying vacuum to the individual hoses. Failure of any of them defaults air to the defrost vents, which is the condition you describe.