7.3 PROTECTION FUNCTION INTRODUCTION (
Sensor T3 (condenser pipe temperature) and T4 (outdoor ambient temperature)
When open-circuit, compressor, outdoor fan motor and reverse valve will be OFF.
When T4 < 5 ° F, compressor will stop.If the electrical heater kit is installed in the
indoor unit, the outdoor unit would provide a signal to drive up the heater.
When T4 > 10.4 ° F, compressor will restart.
Discharge temperature protection (Heat pump only)
When discharge temp. > 275 ° F, compressor will stop.
When discharge temp. < 194 ° F, compressor will restart.
High pressure protection (Heat pump only)
When high pressure > 638 PSIG, compressor and outdoor fan motor will stop.
When high pressure < 464 PSIG, compressor and outdoor fan motor will restart
(3 minutes time-delay necessary).
Low pressure protection (Heat pump only)
Low pressure < 21 PSIG, compressor and outdoor fan motor will stop.
Low pressure > 44 PSIG, compressor and outdoor fan motor will restart
(3 minutes delay necessary).
In stand-by status, the compressor will not start in low pressure protection.
Within 30 mins, if 4 protection cycles occurs, system will restore after power cut-down.
7.4 DEFROST MODE INTRODUCTION
Start-up conditions of defrost mode:
When JUMP switch is set to "1"(See in Fig 11), the mode will start up in either of
the two following conditions:
1. Compressor operating, when T4 is > 28.4 °F and T3 is < 32 °F last for 40 minutes;
2. Compressor operating, when T4 is < 28.4 °F and T3 is < 32 °F last for 50 minutes.
When JUMP switch is set to "0":
Compressor operating, when T3 is < 32 °F last for 30 minutes.
Shut-down conditions of defrost mode:
The mode will shut down in either of the two following conditions:
1. The defrosted time lasting for 10 minutes;
2. T3 is ≥ 77 °F.
JUMP Switch
Fig.11 JUMP Switch Location in the PCB Board
7.5 4-WAY REVERSING VALVE & ACCUMULATOR & DISCHARGE MUFFLER
4-Way Reversing Valve:
When the wall thermostat "calls for heat", the outdoor unit will get signal "B",
the 4-way valve power on, and the unit goes to heating mode. If there is no
signal "B", the 4-way valve stands by and the unit will keep cooling mode.
Accumulator:
To protect the compressor from flood-back & migration.
Discharge Muffler:
Heat Pumps units include Compressor Discharge Muffler.
Heat pump only
20
)