Whirlpool ATE0743RPP, Technical Manual

Page: 64 / 92

6-6
THE REVERSING VALVE
The reversing valve controls the direction of
refrigerant flow to the indoor and outdoor coils.
The valve consists of a pressure-operated
main valve, and a pilot valve that is actuated by
a solenoid plunger. The solenoid is energized
during the “heating” cycle only. The reversing
valve used in the PTAC 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 oppo-
site side is connected to the low pressure
(suction) side of the system. The other two
tubes are connected to the evaporator and
condenser.
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: The sealed system operating pres-
sures must be near normal before the valve
can shift.
Center Tube
Low Pressure
Suction Line
Right Tube
To Condenser
Solenoid Coil High Pressure Inlet Line
Reversing Valve
Left Tube To Evaporator Line