Understanding Air Conditioning Gauges
Anyone interested in understanding how air conditioning gauges work should first take a few moments to understand the refrigeration cycle as well as how the refrigerant flows along the system. This will help you greatly when it comes to identifying both the high and low side of the gauges. You will also learn the role of pressure on the different parts of the system. This is very important since the air conditioning gauges are used to measure the pressure running in the system.
The Basic Air Conditioning Gauges Set
The basic air conditioning gauge set comes in three hoses. The two hoses are attached to the vehicle’s service ports during service. Each of these three hoses has a particular colour for easier identification. In many cases, the hose assigned to the low pressure port is coloured blue, while the hose for the high pressure is red. The middle hose is always yellow; this is attached to the refrigerant’s cylinder while the unit is being charged or to the vacuum while the air and moisture is being evacuated from the system. Your air conditioning gauges should come with a control and gauge knob for both service hoses. Like the hose’s colour, the control and gauge knobs are also coloured to indicate low or high pressure.
What are the numbers on the low and high side air conditioning gauge?
The term compound gauge refers to the low side pressure air conditioning gauge. This means that it can be used to measure either the vacuum or the pressure. The numbers found outside the gauge indicate the PSIG or the pressure in pounds per square inch, while the numbers close to the bottom refer to the vacuum in inches of mercury. The smaller numbers close to the centre of the gauge list the different refrigerants’ temperature relationship. Regardless of what type of refrigerant you are using, the PSI scale is the one that you should use to read the systems pressure, especially when diagnosing or charging an air conditioning system. The working pressure for this air conditioning gauge is between 0 and 120PSI.
The high side gauge is used in measuring the high pressure side of the air conditioning system. This has no markings that may be used to indicate the vacuum. It is only capable of reading positive pressure. Its working pressure is also higher compared to the low side gauge.
The pressure reading seen when the air conditioning is not functioning is called the static pressure. When the temperature is stable while the system is off, the pressure should be very close or the same. This means that both the low and high side of the air conditioning system have equalized.
The Static Pressure when the Air Conditioning Gauges are Hooked Up
There is a specific static pressure for each refrigerant at every corresponding temperature degree. Just remember that the static pressure changes depending on the temperature. Any change in the temperature comes with a change of pressure. The greater the pressure, the greater is the temperature. A refrigerant pressure chart may be used to get the static pressures at different temperatures. The static pressure cannot be used to check if the system is already fully charged.