If an air conditioning system has had 1) refrigerant removed to service or repair the system, 2) refrigerant loss caused by component failure or 3) shows evidence of refrigerant contamination, it must be evacuated to get rid of all moisture and air before it can be recharged with refrigerant. Air and moisture are extracted from [...]
Now that you know how to read the gauges and how to correct for variations in vacuum and pressure caused by different altitudes, you’re ready to hook them up. Pay close attention and you’ll learn how to do it right. Every time you need to diagnose a problem in the air conditioning system, you are [...]
Manifold gauges for 134-a systems work exactly the same was as R-12 gauges. But you can’t use the same set of gauges for both systems. They use completely different couplers and hoses. The gauge face on manifold gauges for R-134a systems have an identification plate that says “for R-134q use only” or something similar. And [...]
The purpose of the manifold is to control refrigerant flow. When the manifold gauges are attached to the system, pressure is indicated on both gauges at all times during normal conditions. During testing, both the low and high side hand valves are in the closed position (turned clockwise all the way until the valve is [...]
An auxiliary gauge may be required for testing older Chrysler vehicles with Evaporator Pressure Regulator (EPR) valves or Fords with Pilot Operated Absolute (POA) valves. It can be either a separate gauge used in conjunction with a two-gauge set or an integral gauge in a three-gauge set. The 0 to 150 psi reading provided by [...]
The low side gauge, which is most easily identified by the BLUE housing and hand valve, is used to measure the low side pressure at the service ports provided on the low side of the system by the manufacturer. The low side gauge pressure scale reads from 0 to between 130 and 150 pounds per [...]
The manifold gauge set is unquestionably the most important tool used in air conditioning system servicing. Nearly all service work performed on automotive air conditioning systems requires the use of test gauges. Test gauges enable a technician to determine the system’s high (head) pressure side and low (suction) side vacuum, determine the correct refrigerant charge, [...]
Systems using R-134a are similar in appearance and function to system using R-12. Although they use physically larger, heavier-duty compressors, condensers and evaporators, cycling clutch, orifice tubes, pressure switches, receiver-driers, etc. – are virtually identical to the parts used on R-12 systems. But they’re not interchangeable! Installing a component designed for an R-12 system in [...]
The evaporator pressure regulator type system (see illustration) is used only on Chrysler Corporation vehicles with a twin-cylinder compressor. Unlike the suction throttling valve (STV) and valves-in-receiver (VIR) units, which are mounted in-line, but outside the compressor, the evaporator control valve is located within the low pressure side of the compressor. The EPR or evaporator [...]
The valves-in-receiver type system is another older General Motors design. The controls – expansion valve and pilot operated absolute suction throttling valve – are located in the same housing as the receiver-drier. This unit is mounted in the high pressure side between the condenser and the evaporator inlet. Like the standard suction throttling valve type [...]