Troubleshooting A/C Problems

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.

Why is my Car Overheating?

It has been a very hot summer so far. Many people are complaining that their car is overheating in these extreme temperatures. When your engine overheats, it can damage the radiator and the engine. It is not a minor thing. So, what might cause a car to overheat? There are a lot of reasons.

First, check the level of coolant in the radiator and overflow bottle. Add a 50/50 mixture of antifreeze to water if it is low. Next, check underneath your car. If there is fluid there, coolant could be leaking from either the radiator or the hoses. You can check the hoses to see if there are cracks or wet spots. If so, replace them. If the coolant is leaking from the radiator, it will need to be replaced.

Next, check the thermostat. If it is stuck in the closed position it will not let the coolant flow into your engine. A good way to check it is to feel the upper part of the radiator hose when the car is warm. It should be warm also. If the hose is not warm, the thermostat is not open and needs to be replaced.

Next, check the radiator cap. It will need to be replaced if it is cracked or if the seal gasket is cracked or gone. If you do not find any problems with the radiator cap, take a look at the water pump. Check the belt to the water pump to make sure it is tight and there are no cracks. The water pump circulates the coolant through the engine. If your water pump is bad, your car will overheat within a few minutes after it is started.

Now take a look at the cooling fan. There are two types of fans, electric and mechanical. If you have a front wheel drive car, it probably has an electrical fan.  This fan will start automatically when your car is warm or when the air conditioning is turned on. The best way to check it is to start your car and turn on the air conditioner. If the fan does not start, it is bad and needs to be replaced.

Cars that have a mechanical fan also have a belt driven fan blade and clutch. The clutch makes the fan run faster when the engine is warm. If there is a problem with it, you will not be able to turn the fan blade easily when the car is off and the engine is cold.

A clogged radiator will also cause your car to overheat. The best way to check it is to have a mechanic pressure check it. If you do not want to spend the money to do that, you can check to see if there is a big difference between the temperature of the upper hose on the radiator and the temperature of the lower hose. If there is, your radiator is clogged and needs to be flushed. When checking this, be careful of the fan blades. You can also use an infrared thermometer to check the radiator for cold spots. Again, if your radiator has cold spots it is probably clogged.