34 PB
COMPONENT TESTING
Reversing Valve Description And Operation
The Reversing Valve controls the direction of refrigerant ow to the indoor and outdoor coils. It consists of a pressure-operated,
main valve and a pilot valve actuated by a solenoid plunger. The solenoid is energized during the heating cycle only. The
reversing valves used in the RAC system is a 2-position, 4-way valve.
The single tube on one side of the main valve body is the high-pressure inlet to the valve from the compressor. The center tube
on the opposite side is connected to the low pressure (suction) side of the system. The other two are connected to the indoor
and outdoor coils. Small capillary tubes connect each end of the main valve cylinder to the “A” and “B” ports of the pilot valve. A
third capillary is a common return line from these ports to the suction tube on the main valve body. Four-way reversing valves
also have a capillary tube from the compressor discharge tube to the pilot valve.
The piston assembly in the main valve can only be shifted by the pressure differential between the high and low sides of the
system. The pilot section of the valve opens and closes ports for the small capillary tubes to the main valve to cause it to shift.
NOTE: System operating pressures must be near normal before valve can shift.
A
B
Figure 603 (Reversing Valve)
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