This is the time of the year when you want the air conditioning in your car to be running at its peak performance. If yours is not, there are some things you can do to fix it.
If your A/C works for awhile, but then begins to blow warm air, it is freezing up. That occurs when there is air and/or moisture in the system. To correct the problem, use a vacuum pump to purge the system.
If you A/C only blows warm or hot air, check the compressor by starting the car and putting the A/C on. If the compressor itself makes a lot of noise or you hear a squeal, it is telling you it is time to replace it. If not, look to see if the compressor clutch is turning. The clutch is located in the front of the compressor. If it is turning, there is enough refrigerant in the system. Most cars have a safety switch that shuts off the compressor if it is too low on refrigerant.
If the compressor clutch is not turning, check to see if it is getting voltage. If it is not, replace the fuse. Then start the car and put the A/C on. If the A/C works for awhile, but the fuse subsequently blows, you have a short somewhere. If the compressor is getting voltage but it is not engaging, the clutch is bad and needs to be replaced. If you feel any liquid around the compressor shaft seal, you should replace that also. Remember, before you replace any parts, the refrigerant must first be evacuated from the system.
One good way to diagnose the system is by using a set of A/C service gauges. The price range for a set of gauges is $50 and up. Attach the gauges to the high and low service fittings on the A/C unit. Then turn the A/C in your car to the highest setting and rev the engine. If both gauges read low, the problem could be with the compressor or that the system is low on refrigerant. Before you recharge the system, check for leaks.
If you have an older car with an R-12 system, you can feel for an oily residue around the compressor, condenser, hoses, etc. Most new cars have an R-134 system. Leaks with this system are harder to find because you will not find any oily residue. Another way to check for leaks is to spray some soapy water on the hoses, connections, etc. Wherever you see a bubble, there is a leak. If you find a leak, you need to replace that part. Unfortunately, if your evaporator or condenser is leaking, the replacement cost will be high. If you do replace the leaky part, you will need to recharge the system afterwards.
If you do not find any leaks, the system could still need to be recharged. That is because all cars leak some refrigerant through tiny pores in the hoses and through the seals. The older the car, the more refrigerant will have leaked. Newer cars have a smaller system capacity than older ones. Therefore, even a small amount of leakage in a newer car can negatively impact its cooling capability.
