Under the hood passen- ger side.next 2 the firewall there is small white vaccume hose that diseergrates.IT is in the wiring harness that comes through the fire wall.U can splice a small piece of vaccume hose 2 repair it.I believe it is a 1/8 inch hose-very small.If U run a new hose U won't have a problem anymore.the original hose will continue to go bad little by little.
Check for vacuum leak either under hood or under dash Check for bad vacuum actuator under dash Defrost is the default setting
A vacuum leak, or one of the doors is sticking/bad vacuum motor in the heater box.
The mixing door isn't working. Take it to the garage as it porbably is the controler. First make sure there is vacuum getting inside the cab from the engine.
dryer sheets in the heater vents may help
your heater core is leaking anitfreeze! heatercoreleaks antifreeze into the heater & ac vents causing a burnt spell & oily film on the front window.
My ac blows only in the defroster and not any of the other vents i have 98 ford windstar 3.8 v6
your switch cable might be broke you will have to remove your dash
The heater may not be on - but the fan still blows air through the vents when they're open !
heater on at idle and will not blow warm air. when moving it blows the warm air from the vents. what will cause this
Your average A/C unit blows heat through all vents.
If it blows only out the defroster vents : then check for Vaccume leak Rick ASE L-1 Master TransMichigan.com
heater core is shot and you have to get a new one
if there is a lot of snow or ice on these vents located at the bottom of the wind shield under the wipers that could be the problem if you live in a cold environment.
sounds like a vaccum line is off. Do you have an aftermarket stereo? I could also be the switch, but I would bet on a vaccum line, search for a diagram then go from there.
The 1984 Buick uses vacuum lines to change air flow from defroster to ac vents. Check the entire vacuum system for leaks.
the middle vents only supply air from the ac unit using a separate in dash fan. the floor and defrost vents come only from the heater
It's either the thermostat or the heater controls.