Service and Parts Manual (2018, 2019, 2020, 2021, 2022)

Table Of Contents
23 PB
OPERATION
Function and Control
Control logic
(a). Turn ON unit: short R and FD then release one time within 5s.
(b). Turn OFF unit: short R and FD then release twice within 5s.
(c). Force unit shut down for one time: short R and FD short over 5s.
NOTE: After forcing unit shut down, you can turn on the unit again by control panel.
For the 24V remote thermostat, it is possible to control the unit with the full functions of DC-Inverter unit, if the main
board has loaded a faulty control algorithm program. Compressor runs in different frequencies according to different
temperature conditions and capacity demands. You don’t need to change the wiring
Protection Functions
To ensure the system running safely, electric control has following protections. For problem solving, please refer to TROUBLE
SHOOTING sections.
1) Outdoor unit overload protection in COOLING mode
When condenser coil temperature exceeds the presetting point, compressor decreases the operating frequency
to 30Hz. If this protection is not enough and condenser coil temperature reaches the shut down point,
compressor will be turned off.
2) Evaporator subcooling protection (will not display error code)
When evaporator coil temperature drops to 1°C and lasts for 5 minutes, compressor and outdoor fan will
stop,but indoor fan keeps on running.
3) Compressor discharge overheat protection
When compressor discharge temperature reaches presetting point, compressor will decrease operating
frequency to 30Hz. If this protection is not enough and discharge temperature reaches the shut down point,
compressor will be turned off.
4) Evaporator overheat protection in HEAT PUMP mode
When evaporator coil temperature exceeds the presetting point, compressor decreases the operating
frequency to 30Hz. If this protection is not enough and evaporator coil temperature reaches the shut down
point, compressor will be turned off. At this time the back-up electric heater will be turned on.
5) Input overcurrent protection
When input current exceeds the presetting point, compressor will decrease the operating frequency to 30Hz. If
this protection is not enough and current reaches the shut down point, compressor will be turned off.
6) Compressor overcurrent protection.
When compressor operating current exceeds the shut down point, compressor will be shut down.