R-22 and R-410a normal temperatur and pressure

On the low side gauge:

R-22: 64 - 81 PSIG
R-410a: 110 - 136 PSIG

On the high side gauge: The range is a lot wider based on seers. The higher seer rating, the lower psig. The lower seer rating, the higher psig.

R-22: 100 - 300
R- 410a: 230 - 325

Cannot charge the system by pressure only due to the cooling days. You will definitely have to look at the superheat.

Use subcooling to charge system if TXV
Use superheat to charge system if Piston

The normal subcooling should be between 8 to 12 degrees. If the target subcooling is not available, then you can normally assume that the target subcooling is 10 or 11, and you should shoot for 11.

The target superheat should be calculated using this formula:

(indoor web bulb temperature x 3 - 80 - outdoor dry bulb temperature) / 2, this will normally give a fairly accurate target superheat, but if the target superheat is posted on the machine or the machine has a superheat target chart, then the chart should be used, the calculation wont be necessary.

Measure the indoor WB as close as possible to the inlet of the evaporator coil, preferably in the return duct a few feet prior to the coil. Measure the outdoor DB roughly one foot away from the inlet of the outdoor coil in the shade.


Reference this chart: 


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