A car owner must know that there are reasons as to why an AC is not working properly. You see, if the coolant levels in your car's air conditioning system is low, it would not be able to produce cold air anymore and there are reasons as to why it is low and it could be due to leaking compressor or break in the O-ring. Other reasons could be a leak on the evaporator lines or condenser. The air conditioner could shut itself down as a way to prevent damage to the compressor due to lack of refrigerant.
To recharge a refrigerant which also labeled as air con regas must need to be done when the leak is repaired. Now, for old vehicles with AC that no longer works, you must be able to have the air con regas done simply because the refrigerant is not producing as much cold air as it used to.
Normally, the common issue as to why a car's air conditioning gets busted is because of the compressor. It serves as the central hub of the entire cooling system. Problem could be about the fact that the compressor clutch may no longer be engaging which simply means that the unit is not going to function properly. It is often signified by a high pitched noise when you turn it on and with this, you must be aware that a repair is not needed but a replacement. Also, a lack of lubrication could be the cause as to why the compressor fails. Low coolant or oil could be the culprit and also if you fail to add oil or if you used the wrong oil, it could lead to compressor failure.
As a car owner, you also need to know that there are two types of air conditioning compressor units: R-12 uses mineral oil and the R-134a requires POE oil. Be careful in applying the oil because if you have the wrong type, the compressor will not work right and would definitely require replacement.
Now, if you want to ask professional help, you could always visit car air con shops. They are known to give excellent service to their customers. They fix AC problems in your vehicle quickly and effectively.