The AC is probably coming through the defroster because the air door is stuck. The door is behind the dash and is vacuum controlled. A vacuum leak or bad door will cause this problem.
One reasons a Dodge W 250 defroster may not work is the blower motor relay. This can be replaced easily. If it isn't the relay, there may be a problem in defroster door binding. A mechanic will be able to determine the cause.
If the heater works but the defroster doesn't on a 1995 Buick Skylark, it could be due to a malfunctioning blend door actuator, which controls airflow between the heater and defroster vents. Another possibility is a clogged or damaged defroster duct, preventing warm air from reaching the windshield. Additionally, low coolant levels or a faulty thermostat could affect the defroster's performance. Checking these components can help diagnose the issue.
your fuse box for a 1992 Chevy caprice, is in the drivers side panel when you open up the door. it is next to the door/window defroster.
Car parts that begin with the letter d:dashboard,defroster,dip stick,dome light,door,door handle,door locks,drive shaft,driver's seat,
This is under the dash and just to the right of your gas peddle.
go to auto parts store and purchase a haynes repair manual
The diverter, or blend, door, is not working properly, The door is either feeding the heat through the defroster, or closing the heat completely off.
Bad fuse
check the fuse Look for a freyed or degraded wire with the rear door open. Located where the door joins the body at the top.
It is probably the sound of the defroster fan.
Some car parts are the dashboard, defroster, diesel engine and dip stick.Some more are the door, door handle, drive belt, drive shaft and driver's seat.