Air conditioning goes from cold air to hot back and forth within minutes of each other

It may need a hvac control unit make sure you check you mode door motor and door as well

Probably a stuck open thermostat or the thermostat is the wrong temp range for your vehicle.

Hi, Sounds like your actuater for your heater box damper is bad. Its munted under the dash over the center hump. you will have to remove the cover that goes the length of the heater box to find it. The actuater motor should move back and forth with the temp knob going from cold to hot.

Try checking your thermostat ,it may be getting stuck .

One of your deflector door servos or the door itself, is hanging up. To determine this more clearly, run your vehicle for about two minutes and shut down the engine. Move your function selector knob from defrost to floor to panel and listen carefully for a sweeeping sound. if you do not hear this sound you've got to check under the dash for a loose vacuum line or under the hood for a loose or broken line to the vacuum accumulator. The vacuum accumulator is a large black ball on the firewall with only two lines connected to it. One line is about3/32nds of an inch and the other will be about one quarter inch. Check these lines well, for they control ALL the functions within yout climate control. Best of luck my friend, Dana

Electical switch dealer part he will wanna sell more stuff anyway.

your high pressure switch is faulty. the part is about 50$

Have you checked the coolant level? If it's low, it will result in diminished heat, and could be the problem.

you have a bad a|c switch and far as gas consumption goes the answer is yes, because if the a|c is always on then there is a constant load on the engine

sounds like you have to much coolant or to little. but first try flushing out your condenser coil in front of your radiator its the cheapest and easiest. and go from there.