Ac System 101
As I have mentioned earlier, AC compressor replacement involves overhauling the whole system and here is why. It comprises of the compressor, condenser, accumulator/receiver dryer, orifice tube/expansion valve, evaporator, hoses and fittings and of course, the refrigerant and compressor oil. Refrigerant is compressed and turned in to liquid. The condenser works to cool the pressurized refrigerant while the receiver dryer separates gas and liquid while absorbing any moisture. The expansion valve then regulates the flow of refrigerant to the evaporator, where the cooling takes place. It then returns to the compressor to start the cycle again.
Things That Go Wrong
Because of the high operating pressures, the most common problem are leaks. The fittings can become lose over time, which can be mended by simply re-tightening and recharging the system. On the other hand, worn out o-rings, broken fittings or a punctured condenser (which is in front of the radiator) will also require servicing. Most people will wait until the refrigerant runs out before having their system checked. I advise people not to do this because continuous use of the AC while there is a leak will end up damaging the compressor even further due to lack of lubrication since the oil is mixed with the refrigerant itself. Another common problem is moisture accumulation, which, is caused by a faulty receiver dryer. This can corrode the compressor therefore damaging it as well. As you can see, any part of the AC system that is left unchecked will eventually lead to compressor failure and ultimately an AC compressor replacement.
Shopping For Parts
You can either go to the dealership to get what you need or shop online for an aftermarket replacement. You also have a choice of purchasing a brand new compressor or a remanufactured one. Remanufactured compressors are simply, new guts in an old casing. They can be a little bit cheaper than the brand new ones but require you to send your old compressor back. Either one would work just fine. It is just a matter of opinion on which is better. It is also necessary to replace the receiver dryer/accumulator whenever you open up the AC system. If you can, throw in a new expansion valve/orifice tube as well.
Only certified mechanics can work on your AC system. Refrigerant is regulated by the EPA and not anyone can purchase it without proper credentials. Unfortunately, this will also mean hourly costs will be expensive which is why, it is best to do the whole 9 yards when fixing the AC in your vehicle. AC compressor replacement can be very expensive but proper service of the AC system will give you years of trouble-free AC performance.