17
When T4< 5°F, the outdoor unit would provide a signal to drive up
the heater installed in the indoor unit.
In stand-by status, the compressor will not start in low pressure
protection. Within 30 minutes, if 4 protection cycles occur. The
system will be locked. It will be restore after power cycle.
15. System operation and troubleshooting
15.1 Compressor crankcase heater (CCH)
(Heat pump only)
15.2 Reversing valve (Heat pump only)
15.3 Protection function (Heat pump only)
15.4 Protection function (Air conditioner only)
15.5 Defrost mode (Heat pump only)
The crankcase heating start must meet two conditions:
A. Outdoor temperature
＜
37.4°F
B. At power up or if the compressor has been off for more than 3
hours
The crankcase heating stop must meet the following condition:
Outdoor temperature
＞
44.6°F or compressor starts.
Reversing valve energizes at the heating conditions, and cuts off at
the cooling condition.
Manual defrost mode
When the switch SW3-1 is set to “ON”, the system turns to the
defrost mode. The defrost mode exits by the logic of shut-down
conditions of defrost mode.
Start-up conditions of defrost mode
When SW3-3 switch is set to “ON” (Figure 4), the mode will start up
in any of the following conditions:
Figure 42
T3 = Outdoor Coil Temperature
T3
＞
143.6°F, compressor stops working
T3
＜
125.6°F, compressor restarts working
T4 = Ambient Temperature
T4 < 5°F, compressor stops working
T4 > 10.4°F, compressor restarts working
If 55°F ≤ T4 ≤ 115°F, unit can operate in cooling
If 5°F ≤ T4 ≤ 75°F, unit can operate in heating
Once the manual defrost mode is finished, please turn the switch
SW3-1 back to “off ”.
Discharge temperature protection
Discharge temperature > 275°F, compressor stops working.
Discharge temperature < 194°F, compressor restarts working.
High pressure protection
High pressure > 638 PSIG, compressor and outdoor fan motor
stop working.
High pressure < 464 PSIG, compressor and outdoor fan motor
restart working (3 minutes delay necessary).
Low pressure protection
Low pressure < 21 PSIG, compressor and outdoor fan motor
stop working.
Low pressure > 44 PSIG, compressor and outdoor fan motor
restart working (3 minutes delay necessary).
Compressor operates and T3 < 32°F for a period of 30
minutes.
T3 < 28.4°F and compressor operates for the first time after
connected to the power source.
When T3 < 28.4°F and the system is on standby for two hours
continuously.
When SW3-3 switch is set to “OFF”(Figure 41), the mode will start
up in any of the following conditions:
Compressor operates and T3 < 32 °F for a period of 60
minutes.
T3 < 28.4 °F and compressor operates for the first time after
connected to the power source.
When T3 < 28.4 °F and the system is on standby for two hours.
Shut-down conditions of defrost mode:
The mode will shut down in any of the following conditions:
The defrosted time lasts 10 minutes
T3 ≥ 64.4°F and T4 ≥ 28.4°F
Compressor stops operating
T3 ≥ 64.4°F lasts 60 seconds when T4 < 28.4°F
The location of SW3 Switch in the PCB Board
High pressure protection
High pressure > 638 PSIG, compressor and outdoor fan motor
stop working.
High pressure < 464 PSIG, compressor and outdoor fan motor
restart working (3 minutes delay necessary).
SW3 Switch
