A/C Cycling Switch

As described previously under AC Compressor and A/C Clutch Assemblies, the A/C cycling switch (19E561) is mounted on a Schrader valve on the accumulator/drier assembly. A valve depressor, located inside the threaded end of the A/C cycling switch, depresses the Schrader valve stem as the switch is mounted and allows the suction pressure inside the accumulator/drier housing to control the operation. The electrical contacts are normally open when the suction pressure is at or below 152 kPa (22 psi); they will close when the suction pressure rises to approximately 276-317 kPa (40-47 psi) or above. Lower ambient temperatures (below 10°C or 50°F), during cold weather seasons, will also open the contacts due to the pressure/temperature relationship of the refrigerant in the system. The electrical contacts control the circuit to the A/C clutch field coil (2987). When the contacts are closed, the A/C clutch field coil is energized and the A/C clutch (2884) is engaged to drive the A/C compressor (19703). When the contacts are open, the A/C clutch field coil is de-energized, the A/C clutch is disengaged and the compressor does not operate. The A/C cycling switch, when functioning properly, will control the pressure in the A/C evaporator core (19860) at a point where the plate/fin surface temperature will be maintained slightly above freezing, which prevents icing and the blockage of airflow.

A/C Evaporator Core and Suction Accumulator/Drier

Item	Part Number	Description
1	—	Outlet to Compressor
2	19C836	Suction Accumulator/Drier
3	—	To Suction Accumulator/Drier
4	—	From Condenser
5	19860	A/C Evaporator Core