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

18 PB
OPERATION
Function and Control
When 32°F < T4 < 44°F, unit will run in electric heating mode to meet the rst cycle demand. From the second
cycle on, heat pump will operate.
When T4≤32°F, the E-heater will operate exclusively.
During heat pump mode, once T3 freezes to 5°F, or any fault occurs, unit will switch over to electric heating
mode.
Outdoor fan control in heat pump mode:
When T4 is above 57°F, outdoor fan runs at low speed to lower the noise;
When T4 drops to 53°F, outdoor fan runs at high speed, in order to ensure the heating capacity.
Electric heating mode:
The unit is equipped with a universal E-heater, which contains two independent heating elements. The 9K BTU unit
incorporates a 2.5kW and a 1.0kW element. The 12K BTU unit incorporates a 3.5kW an s1.5kW element.
Power Cord Selection
Use the appropriate power cord for each heating configuration as shown in the table below.
Power Cord 15A 20A 30A
9K BTU Unit 2.5kW 3.5kW N/A
12k BTU Unit 1.5kW 3.5kW 5kW
Indoor fan control in heating mode:
The indoor fan will run synchronously with the heating demand. During no demand period, it will run
for 30s(heat pump) or 1min(E-heating) after CONSTANT FAN button is turned off, then turns OFF. When
CONSTANT FAN is ON, it will always berunning.
Defrost
In heat pump mode, if the compressor runs continuously for over 30 minutes and T3< 26°F, or runs continuously
for 90 minutes and T3<32°F the unit will enter defrost stage. Indoor fan will shut down. After the defrosting cycle is
finished, the unit turns to E-heating for the first cycle to heat up quickly.
3) Room Freeze Protection (AUTO HEATING)
This is valid only in standby mode. The dual 8 digital tube displays “L0”.
Entry condition: #5 DIP SWITCH is set to ON to enable the indoor freeze protection and the main board detects
the indoor ambient temperature is lower than 50°F(10°C) for 3 consecutive minutes.
Quitting condition: When indoor ambient temperature rises to 55 °F(13°C), the heating will stop.
4) Temperature Sensor Open Circuit or Short Circuit Protection
If the temperature sensor has an open circuit or a short circuit, the ERROR CODE will display on the digital
tube. If the malfunction of the temperature sensor is detected for 30 seconds, the unit will turn off.
5) Power cut protection
After power cut recovery, unit will have a time delay of 2 to 4 minutes to restart E-heating. The DC-inverter soft start
compressor will restart after 3mins.
6) Compressor and DC-inverter features
The DC-inverter compressor has a high efciency rating and energy savings can be 30% to 80%. Operation
voltage range is 160VAC~270VAC, making the unit operation more stable under a wider voltage range power
input. With its soft start feature, power surges can be avoided, and also lower the noise level. Without the
frequent start-stop, room temperature will be more stable and more comfortable.
The high performance IPM contains a PFC module and under heavy loading PF can be up to 99%, thus
decreases EMI pollution to power supply system, and also decreasing power surges.
The compressor driver chip is high performance, making the compressor more stable and reliable