ac charge -low side, high side

[Tallbrad]

79sc.. I am having senior moment and need a quick answer please .... which is the low pressure side ? thick black tube that runs to the front of the car or the skinnier one that runs to the condenser on the engine lid ?

Thanks Gang,

JB

[ShakinJoe]

JB,

The low side usually has a blue cap, and the high side has red. If you don't have those, then do this. Look at your compressor and follow one of the lines that feeds directly to the rear condenser. That is your high side. The low side actually is RETURNING to the compressor form your evaporator.

If you are pulling a vacuum on the system, I suggest to evacuate on BOTH sides.

Charge to the low side......always.

Joe

[tcar]

Originally Posted by Tallbrad

79sc.. I am having senior moment and need a quick answer please .... which is the low pressure side ? thick black tube that runs to the front of the car or the skinnier one that runs to the condenser on the engine lid ?

Thanks Gang,

JB

The thick black tube runs FROM the front of the car, not TO the front of the car, its FROM the evaporator. Low side.

[3.2 CAB]

I am not sure which A/C compressor you might have, but... most will have the "high" and "low" sides marked. The "low side" on most that are marked will have an "S" or "SUC" for suction, and will have a "D" or "DIS" for discharge. The suction port is the low side port(which is the "blue side"), while the discharge port is the high side port(which is the "red side"). Hope this helps. Good luck!! Tony.

[tcar]

If it's stock, the compressor is the MIGHTY YORK. Big. No red, no blue. Just the entire daily output of some aluminum mine.

[kuehl]

The low side of the ac system starts at the evaporator outlet and ends at the compressor inlet. On a factory air ac system on the SC that would be the largest diameter hose connected to the compressor. The high side starts at the compressor outlet and ends at the expansion valve. When we talk in terms of "starts" or "ends" we are simply thinking of terms of flow of the system through the refrigerant cycle.

Pressure measurements are usually taken at the compressor's service ports, sometimes called schraderr valves (the schrader valve is actually located inside the service port). The service ports can be located in various places on or near the compressor: such as on the compressor's body, on the hose fittings attached to the compressor, or in the case of a stock factory SC the service ports will be on the service valves attached to the York compressor. Not all service ports have colored caps; and depending upon the type of refrigerant you are using the service ports can be different shapes.

Before we start off down the wrong road, beyond your question, why don't you give us an idea on what you want to do, because if you are attempting to charge or top off the system you don't want to charge with "liquid" through the low side. Low side is for vapor/gas only, and usually this is done with the system running. If you wanted to charge through the high side you would use liquid rather than vapor: can upward for gas, can downward for liquid.

If you need more help let us know what make compressor you have, a picture is always best.