Pressure Cycling Switch

A switch that senses the low-side pressure as an indicator of evaporator temperature controls the refrigeration cycle, the on and off operation of the compressor. The pressure cycling switch is the freeze protection device in the system. The switch senses refrigerant pressure on the suction side of the system. The switch mounts on a standard service low-side fitting. This switch also provides compressor cutoff during cold weather.

Additional compressor protection results from the operating characteristics of the low-side pressure cycling system. If a massive discharge occurs in the low side of the system, or the orifice tube becomes plugged, low-side pressures may be insufficient in closing the contacts of the pressure switch. In the event of a low charge, insufficient cooling accompanied by rapid compressor clutch cycling is noticeable at high outside or ambient air temperatures.

Do not remove the refrigerant charge in order to replace the pressure cycling switch. The pressure switch fitting has a service fitting. During the replacement of the pressure switch, install a new O-ring seal. Assemble the switch to 4.5 N.m (40 lb in).