AC in a vehicle has 5 major parts.
Compressor is on the engine, fan belt turns it to compress the low pressure liquid Freon(yes I know not Freon any more, lol), and that turns it from a liquid into a gas at high pressure
From the compressor the now high pressure Freon gas goes to the condenser, it is on the front side of the radiator.
Compressing anything heats it up, the condenser cools it off.
From the condenser the partially cooled Freon is back to a liquid, but still at high pressure, and goes to the Drier, this absorbs any moisture from the heating and cooling of the Freon
From the Drier it goes to the Expansion valve.
When you allow a compressed(high pressure) liquid(or gas) to drop to a lower pressure it cools down rapidly, the point of AC, and refrigeration in general.
If you have an air compressor or a can of compressed air, when you release the air it is very cold when it comes out, thats how AC works, compress and decompress
from expansion valve it goes to Evaporator in the cab, it gets this now very cold low pressure Freon running thru it, and a fan blows air thru evaporator tubes and fins and out the vents.
From evaporator the Freon liquid goes to compressor, and process starts all over again
If you have a leak in the system, anywhere really, then Freon need to be drained and that part replaced, then the system needs to be recharged again.
There are also 2 pressure switches, one on high side the other on lower side.
If there is a leak one of the pressure switches will open so compressor can't start.
Compressor is oiled internally by the Freon, if pressure is low then running the compressor will cause to to fail, burn up inside.
Evaporator is the only part in the cab, the rest are in the engine bay, or in front of rad
Last edited by RonD; 06-16-2016 at 11:25 AM.