You uniformly adjust pressure limits on an air compressor unit. The procedure is used to prevent accidents and most air pressure limit switches can be adjusted at home. Take a look at the device and locate a large metallic screw. This is used to adjust cut-in pressure. Locate a small metallic screw which is used to adjust cut-out pressure.
Step 1 - Open Air Compressor Compartment
Do not wear loose-fitting clothes when making changes in the air compressor unit. Locate the air compressor compartment on the air conditioner system and remove the cover.
Step 2 - Adjust Differential Pressure
If all wires are in place, observe the pressure gauge and allow pressure to build in the tank. When it is full, it should kick off at approximately 150 psi, which is the cut-out pressure (or the pressures suggested in your owner's manual). Open the drain cock to let out air while observing the pressure gauge. The compressor unit should kick in at about 120 psi, which is the cut-in pressure.
Step 3 - Check Pressure
Close the drain cock and check whether cut-in and cut-out pressure is as provided by the manufacturer, give an allowance of ± 5 psi. Turn off the power supply to the air compressor. Loosen screws and remove the pressure switch cover. Make adjustments by turning the pressure adjustment screw by cutting in pressure and using the differential adjusting screw to cut out pressure.
Finish by replacing the cover and turning on the unit.