I have not had any air coming from the heater of my 92 S10 Blazer for months now. You can hear a load hissing (vacuum leak) in the vent control area on the dash.
I went to a junk yard and got a new unit, replaced mine and the leak is now gone. The little part that all the hoses connect to was leaking badly.
I still do not have any heat. If I reach down behind the vacuum assist on the heater area there is a spring loaded metal arm on the side of the duct area. If I grab it and pull on it I have heat. If I manually move it back I don't.
Is this part of the vacuum assist assembly or a separate part?
Can it be replaced?
Lannie