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High side and low side refer to the pressure in the ac system. Ie The high side is the high pressure line and low side is the low pressure line.
R12 Low Side 7/16 in. threaded ß----------à R134 Low Side 13mm Quick-disconnect R12 High Side 3/8 in. threaded ß----------à R134A High Side 16mm Quick-disconnect
The low pressure side generally has a different fitting than the high side so your kit should only attach to one side. The low side generally has a larger size hose connected to it also.
normal low side operating temperature for an AC system using R134-a refrigerant is between 21 and 35 p.s.i. high side pressure between 190-220 p.s.i.
It is in the last place you would think. P.s. Its in plane sight R12 Low Side 7/16 in. threaded ß----------à R134 Low Side 13mm Quick-disconnect R12 High Side 3/8 in. threaded ß----------à R134A High Side 16mm Quick-disconnect On older R12 systems, the LOW and HIGH pressure service fittings are screw-type Schrader valves. On newer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOW pressure fitting is SMALLER than the HIGH pressure fitting.
If the pressures are always equal running, the compressor is bad and would need replaced
Low side.
R12 Low Side 7/16 in. threadedß----------à R134 Low Side 13mm Quick-disconnect R12 High Side 3/8 in. threadedß----------à R134A High Side 16mm Quick-disconnect
LOCATE THE SERVICE FITTINGS Next, you need to locate the service fittings on the A/C system. There are two: a LOW side fitting and a HIGH side fitting. The LOW side fitting is usually located on the suction hose or line that goes from the accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressor to the condenser. R12 Low Side 7/16 in. threaded ß----------à R134 Low Side 13mm Quick-disconnect R12 High Side 3/8 in. threaded ß----------à R134A High Side 16mm Quick-disconnect On older R12 systems, the LOW and HIGH pressure service fittings are screw-type Schrader valves. On newer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOW pressure fitting is SMALLER than the HIGH pressure fitting.
The compressor changes the low pressure gas into a high pressure gas which then has the heat of compression removed in the condensor to turn it into a high pressure liquid.
LOCATE THE SERVICE FITTINGS Next, you need to locate the service fittings on the A/C system. There are two: a LOW side fitting and a HIGH side fitting. The LOW side fitting is usually located on the suction hose or line that goes from the accumulator to the compressor. The HIGH side fitting is located on the line that goes from the compressor to the condenser. R12 Low Side 7/16 in. threaded ß----------à R134 Low Side 13mm Quick-disconnect R12 High Side 3/8 in. threaded ß----------à R134A High Side 16mm Quick-disconnect On older R12 systems, the LOW and HIGH pressure service fittings are screw-type Schrader valves. On newer R134a systems, the LOW and HIGH side service fittings are quick-connect style fittings. The LOW pressure fitting is SMALLER than the HIGH pressure fitting.
Always to the low pressure side. The low pressure side fitting is normally near the dryer ( large silver canister).