Midea 16 SEER - Protection Function Introduction; Defrost Mode

16
7.3 PROTECTION FUNCTION INTRODUCTION (Heat pump only)
Sensor T3 (condenser pipe temperature) and T4 (outdoor ambient temperature)
When open-circuit, compressor, outdoor fan motor and reverse valve will be OFF.
Discharge temperature protection
When discharge temp. is > 275 °F, the compressor will stop.
When discharge temp. is < 194 °F, the compressor will restart.
High perssure protection
When high pressure is > 638 PSIG, the compressor and the outdoor fan motor will stop.
When high pressure is < 464 PSIG, the compressor and the
outdoor fan motor will restart
(3 minutes delay necessary).
Low pressure protection
Low pressure is < 21 PSIG, the compressor and the outdoor fan motor will stop.
Low pressure is > 44 PSIG, the compressor and the 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.
When T4 is < 5 °F, the 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 is > 10.4 °F, the compressor will restart.
Error code table for the indicating light:
STEADY ON = NORMAL OPERATIONSTEADY ON = NORMAL OPERATION
OFF = DFC FAILURE OFF = DFC FAILURE
1 FLASH = T3 SENSOR FAILURE1 FLASH = T3 SENSOR FAILURE
2 FLASH = T4 SENSOR FAILURE / HPC OR HGS OPEN2 FLASH = T4 SENSOR FAILURE / HPC OR HGS OPEN
1
2
0
3 FLASH = LPC OPEN3 FLASH = LPC OPEN
3
When JUMP switch is set to “0”:
Compressor keeps running, when T3 is < 32 °F and last for 30 minutes.
7.4 DEFROST MODE* (For HP system only)
Defrosting condition:
When JUMP switch is set to “1”, the defrost mode will start if one of following
conditions is satisfied:
1. Compressor keeps running, when T4 is > 28.4 °F and T3 is < 32 °F and last
for 40 minutes;
2. Compressor keeps running, when T4 is < 28.4 °F and T3 is < 32 °F and last
for 50 minutes.
* When defrosting actions, if the electrical heater kit is installed, the unit would deliver the Aux. heater
operation signal to the electrical heater kit.