there are a few things that will cause this, relay or fuse to ac blown, if low on freon ac will not work. check and see if clutch on ac motor works. if not its the relay.
Check the Freon pressure first. The AC compressor will not turn on if the Freon pressure is too low.
The AC pump is bad. When the AC is turned on the pump tries to turn, because it is bad the extra strain on the motor causes it to stall. Be carely this can break or through a belt. In short its like putting a "brake" on your motor.
You may need to replace the heater\ac control switch, it may be stuck in the off position which would prevent the blower and the ac compressor from turning on.
90 percent is the compressor relay that cause it.
when the AC is on it puts more stress on the engine cause the engine has to now turn the compressor. which in turn adds more heat to the engine.
The blower motor speed switch is burned out or the fuse is blown.
Mold.
AC idle compensator. Many vehicles have a sensor that increases idle speed when you turn on & add more load. Sounds like your idle not being adjusted. Have your mech check it.
check the vacuume lines Need more info, do you mean the blower is losing volume? BClear.
AC runs on the battery. If the car is off and you run the AC, then start the car, it will stall.
Most common problem LOW FREON