Friedrich WallMaster PE07K, Руководство по обслуживанию

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Metering Device
Capillary Tube Systems
All units are equipped with capillary tube metering de-
vices.
Checking for restricted capillary tubes.
1. Connect pressure gauges to unit.
2. Start the unit in the cooling mode. If after a few
minutes of operation the pressures are normal,
the check valve and the cooling capillary are not
restricted.
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
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 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 .
DANGER OF BODILY INJURY OR DEATH
FROM ELECTRICAL SHOCK
The reversing valve solenoid is connected to
high voltage. Turn off electrical power before
disconnecting or connecting high voltage wiring
or servicing valve.
3. Switch the unit to the heating mode and observe the
gauge readings after a few minutes running time. If
the system pressure is lower than normal, the heating
capillary is restricted.
4. If the operating pressures are lower than normal in both
the heating and cooling mode, the cooling capillary is
restricted.