Capillary Tube Systems; Reversing Valve Description/Operation; Electrical Circuit And Coil; Testing Coil - Friedrich H)A09K25 Service Manual

Metering Device - Capillary Tube Systems
All units are equipped with capillary tube metering devices.
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
Vert-I-Pak 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.
WARNING
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.

Electrical Circuit and Coil

(Reversing valve coil is energized in the heating cycle only).
1. Set controls for heating; valve should shift.
2. Check for line voltage at the heat relay, terminal #2
and L2 at the quick disconnect. If line voltage is not
present check the power supply.

Testing Coil

1. Turn off high voltage electrical power to unit.
2. Unplug line voltage lead from reversing valve coil.
3. Check for electrical continuity through the coil. If you
do not have continuity replace the coil.
4. Check from each lead of coil to the copper liquid line as
it leaves the unit or the ground lug. There should be no
continuity between either of the coil leads and ground;
if there is, coil is grounded and must be replaced.
5. If coil tests okay, reconnect the electrical leads .
6. Make sure coil has been assembled cor rectly.
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