Bad vac line or cable to your vent controls. There is a door to your heater core that is supposed to closed when ac is on-yours is not. A place that does ac repairs can check it out for you.
Perhaps a dead mouse.
your heater core is leaking anitfreeze! heatercoreleaks antifreeze into the heater & ac vents causing a burnt spell & oily film on the front window.
It is called condensation.
replace? why not fix it?
From the vents or from an AC line? If you're tracing your lines, and you feel heat coming off of the smaller lines, that's normal... refrigerants gets heated and superheated as it cycles.. the operation of AC is a series of heat exchanges.If you're getting it out of your vents, then there's a condition in your system which is preventing the AC system from providing sufficient cooling. It could be a number of reasons why, and AC diagnosis really isn't a do-it-yourself task.
it is the moter that spins the fan that blows your heat or ac out of your vents
Nope, that would be steam.
AC VENTS are in the correct position if they are open and free flowing. Some systems have a heat and an AC position for the vents. The AC position is so the cool air discharges from the vents higher on the walls or from the dash rather than floor or windshield in a car.
The musty smell coming from your AC vents could be caused by mold or mildew growth in the system. This can occur due to moisture buildup in the ducts or filters. Regular cleaning and maintenance of your AC system can help prevent this issue.
If your 03 Trailblazer blows heat out of the back vents when set on AC sometimes, it could be because of a faulty blower motor resistor block.
The most likely reason is your AC system needs recharged.
assuming this is Home AC question - speed up the AC fan speed