System Operation And Troubleshooting - Trane Oxbox AC Series Installation Instructions Manual

15. System operation and troubleshooting

15.1 Compressor crankcase heater (CCH)
(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.
15.2 Reversing valve (Heat pump only)
Reversing valve energizes at the heating conditions, and cuts off at
the cooling condition.
15.3 Protection function (Heat pump only)
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
When T4< 5°F, the outdoor unit would provide a signal to drive up
the heater installed in the indoor unit.
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).
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.
15.4 Protection function (Air conditioner only)
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).
15.5 Defrost mode (Heat pump only)
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.
Once the manual defrost mode is finished, please turn the switch
SW3-1 back to "off ".
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:
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
SW3 Switch
The location of SW3 Switch in the PCB Board
Figure 42
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