Air conditioning leaks
Auto air conditioning leaks are the most common cause of automotive AC systems not blowing cold air. What can happen is the vehicles Freon will leak out and reduce the total pressure in the system. Then the low-pressure cut out switch will disengage the compressor when the low side is detected below 25 psi. This safety feature is to protect the compressor itself. I have seen mechanics bypass the low cut out switch for testing. This should never be done and is not recommended.
Note that when the system pressure is low and the compressor clutch disengages it is just like having the AC switch turned off completely. Therefore testing the refrigerant system for leaks is one of the most important tasks when troubleshooting automotive air-conditioning systems. Keep in mind that over a period of time, all air conditioners will lose or leak out some refrigerant. Even in systems that are in good condition. They say that on average, an AC system could lose up to 5 ounces of Freon A year and this would be considered a normal condition.
Finding auto air conditioning leaks
As I mentioned before in previous articles about how the air-conditioning system works. The Freon contains the oil necessary to lubricate the compressor. The presence of oil around a fitting or line is a strong indication of a refrigerant leak. So my first step in air-conditioning leak diagnosis is to perform a solid visual inspection of the entire system. Although this is always my first step for diagnosing Freon leaks it is not always effective in finding the problem. In fact, this visual inspection will only uncover large to extremely large leaks. And by far the most common air-conditioning problem would be small leaks that allow Freon to escape over long periods of time. So to follow will be methods to detect these small leaks.
Electronic automobile A/C leak detectorsThis is the preferred method of leak detection because it is safe and effective and can be used with all types of refrigerants. The Robinair leak detector is a hand held battery operated electronic leak sniffer. The test probe on the end of the leak detector is moved about 1 inch per second in the areas of suspected leaks. I usually go for the high pressure side fittings and O-rings first. Also note that the refrigerant is heavier than air. So I will run the leak detector just below these fittings and lines. The Robin air leak detector has an alarm that will go off when it detects the presence of a Freon leak. Note on some other models they may have flashing lights or a buzzer, but they all are designed to alert you when they sniff the refrigerant.
Fluorescent dye auto leak detectors
Most auto repair shops that I have worked at including the one I work at now has a fluorescent dye tracer system for finding stubborn leaks. To find refrigerant leaks using the fluorescent tracer system, you first have to install the fluorescent dye into the cars air-conditioning system. Always follow the instructions and do not install too much dye!Different refrigerant dye leak detectors will accomplish this in different ways. The system we use has a device that looks like a caulking gun, and a hose that connects to the low side fitting. Then you actually push the dye in to the low side of the system. Next you run the air-conditioning system for several minutes to distribute the dye evenly. Then you put on your yellow glasses and examine the system with a fluorescent light.
But when I examined the evaporator case inside the vehicle, the fluorescent dye was laying in a large puddle on the bottom of it. This meant the evaporator itself needed replacement. Not a fun job on most vehicles.
Air conditioning leaks sealer for cars
A very popular selling item is Refrigerant with leak sealer. This item will only seal very small leaks. I have used the stuff pictured to the right "super seal pro" and it does work, in some situations. The Freon leak sealer works best when you have low side system leaks. And if you happen to have a small leak from an O-ring on the low side, this stuff works well. If you have a leak on the high-pressure side, chances are this sealer will not work for you. Although if the leak is small enough and from an O-ring on the high side there is a 50-50 chance that the Freon stop leak will help. And when I say help, I mean that it will even slow the leak down further, but it will most likely still leak. The most common scenario from using an air conditioner leak sealer is that the system will still leak, but may only need to be charged once a year.
Just remember I mentioned that it may not work at all and you will wind up having to diagnose your air conditioning leaks and make physical repairs.
Look through both of my auto repair websites at the same time.  Custom Search If you need specific car repair instructions for replacing air conditioning components on your particular automobile then you will need this car repair manual On the you fix cars home page you'll find a brief rundown of what else is available on this auto repair website. You'll also find more information about the mechanic that built it and why he thinks a lot of people can do their own Diy car repairs
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