The air conditioner smells like burning plastic when you turn it on and smoke comes out the vent. What could it be?

Check under hood. may not have been coming from your car.

have an accredited ac shop as an ac cannot produce hot air only cold air so that means that the ac is not working (leaks low on gas etc). The hot air is from the heater in the car and the smell is probably wire overheating or the resistors are burning.

If it is smoke you will smell it as if there is burning plastic. Some ac units produce really cold air and what you may be seeing is frosted air from the evaporator coming out the vents. It is an indication that the evaporator is actually icing up and not working efficiently.

you more than likely have a sciezed air con compressor. most modern cars have climate control which uses air con even when demisting and when engaged the electric clutch tries to engage but the pump itself will not turn, clutch will get red hot and burn your belts

Is it smoke or water vapor? If it's smoke, you probably have an electrical problem somewhere. If it's water vapor and you live in a very humid climate, it should dissipate soon after turning on the A/C. Is there a noticeable smell (burning plastic?) along with the smell? If so, have your car checked out by a qualified technician - it could be a fire hazard.

usually due to high humidity in the conditioned space. if you dont smell smoke or heat let ir run and see if it stops when it gets the humidity under control

do you turn on fan when using a/c ! if so heres a few causes-- burning smell in car, blower motor is going bad, or resistor is burning up.the resistor controls the fan speeds. good-day !

The burning smell could be due to gas leakage in the engine compartment. The gas smell is being sucked into the fresh air intake of the air conditioner. It can be avoided by checking either fuel pressure regulator or fuel injector.

Usually if it's new, there will be some burn off. Make sure propane detector and smoke alarm, as well as carbon monoxide detector, if you have one, are working. Smell and any smoke should burn off after running a while, if not have it checked to be sure. I'd recommend running it with windows open and roof vents open and any exhaust fans at stove, and roof vents turned on for a while, then shut it off, let trailer air out good, then close windows etc, and see if it's better.

something near the a/c vent (under your hood) started to burn or burnt something stuck in there like leaves or plastic etc. check your lines and fuels, make sure nothing's leaking or dried up.

no worse than smoking a couple of cigarettes. she will be OK