You may need to recharge your a/c compressor with coolant.
For vehicles which are intended to have an air system (e.g., Class 7/8 trucks with air brake systems), those use a gear driven air compressor which is mounted on a plate attached to the engine block. Yes, coolant goes into those. For aftermarket add-on ones, which are typically belt or chain driven, no.
If it is too low on coolant the ac compressor will not engage. It is a safety feature to keep from burning it up. Try to add freon and as the pressure builds the compressor should kick on. If you are sure you have adequate coolant; it could be anything from electrical to a frozen compressor.
You will have to replace the refrigerant, but not the engine coolant.
The pressure in the can of coolant you are adding is usually enough to start the compressor howerver you must have the air conditionig switched on in the vehicle.
its best to have a shop do it because the air needs to be vacuumed out and the freon needs to be put in with out any air at all or it will crack your compressor
air conditioning compressor
a cracked air compressor
check all A/C electrical connections, like the connector at the compressor.. make sure the compressor is trying to engage, should be an audible click when switched on, check fuses, also check pressure switch on coolant line.. it has a electrical connector on it also, and if coolant is low it will not let the compressor engage.
Typical causes of a compressor not running are: low coolant, blown fuse in compressor circuit, bad compressor, bad temperature sensor.
compressor, condenser, radiator(not your coolant radiator, its the smaller one infront), and evaporator are the four components
A lot of cars won't let the compressor kick on unless it has enough refridgerant. Try recharging the compressor all the way and if it still don't work, you might need a new compressor.