Testing AC Operation

Here are some characteristics to look for under the hood with the system turned to high.

? The lines, hoses, and components in the low side of the system should be cold and likely will have water droplets dripping from them.

1 63 Testing AC Operation

It is very common to see water droplets dripping off of components in the low side, such as the suction line and the accumulator dryer, and for them to be cold when the AC is operated on a hot

? The lines, hoses, and components in the high side of the system should be hot, which is best to be tested with a laser thermometer since the surface temperature of these components will range from 100 to 220°F.

1 64 Testing AC Operation

The components on the high side of the system are usually at a high temperature while the system is operating. This is a result of the high pressure that is present in the high side

? The compressor should be operating without much audible noise and it may be cycling off and on in order to control the temperature of the evaporator.

? The cooling fan will likely be operating if the ambient temperature is high enough to cause the high side pressure to reach moderate levels. The cooling fan often runs with the AC when the vehicle is stopped in order to cool the condenser, but the fan typically shuts off when the vehicle is being driven at highway speeds, which provides plenty of ram air to cool the condenser.

1 65 Testing AC Operation

The cooling fans are vital to the operation of the AC system. These fans run to pull air through the radiator and condenser, which removes heat from these heat exchangers and allows the engine to be cooled as well as the AC system to operate

? The duct air is directed from the passenger vents and is moving at a high velocity since the blower is set to high speed.

1 66 Testing AC Operation

The temperature of the air coming out of the air ducts should be in the range of 40 to 50°F when the AC system is set to maximum and the blower is set to high

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