GSZH5 Service Manual

60
SYSTEM OPERATION
Heating Cycle
The reversing valve on the GSZ, SSZ, ANZ, ASZ, DSZ
GSZH5 and ASZH5 models is energized in the cooling
cycle through the “O” terminal on the room thermostat.
These models have a 24 volt reversing valve coil. When the
thermostat selector switch is set in the cooling position, the
“O” terminal on the thermostat is energized all the time.
Care must be taken when selecting a room thermostat.
Refer to the installation instructions shipped with the
product for approved thermostats.
When the room thermostat calls for heat, the contacts of
the room thermostat close making terminals R to Y & G,
the low voltage circuit of the transformer is completed.

compressor contactor (CC) and fan relay (RFC).
This draws in the normally open contact CC, starting the
compressor condenser fan motors. At the same time,
contacts RFC close, starting the indoor fan motor.

breaking the low voltage circuit, causing the compressor
contactor and indoor fan relay to open, shutting down the
system.
If the room thermostat fan selector switch should be set
to the “on” position, then the indoor blower would run
continuously rather than cycling with the compressor.

are sent to the UC control. The compressor relay and
outdoor fan relay is de-energized. The compressor high
stage solenoid is de-energized if it was energized. The UC
control sends an appropriate command to the indoor unit to
de-energize the indoor blower motor.
Indoor
Coil
Accumulator
Bi-Flow
Filter Dryer
Outdoor
Coil
Thermostatic
Expansion
Valve
Check Valve
Reversing Valve
(De-Energized)
Indoor
Coil
Accumulator
Bi-Flow
Filter Dryer
Outdoor
Coil
Thermostatic
Expansion
Valve
Check Valve
Reversing Valve
(Energized)
Heating Cycle