Friedrich Twintemp, Service Manual

Page: 34 / 68

NOTE: System operating pressures must be near
normal before valve can shift .
rEvErSING vALvE dESCrIPTION/OPErATION
The Reversing Valve controls the direction of refrigerant
flow 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.
ELECTRIC SHOCK HAZARD
WARNING
Disconnect power to the unit before servicing.
Failure to follow this warning could result in
serious injury or death.
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