8.4 Thermostat Signals
Start-up conditions of defrost mode
When SW3-1 switch is set to “ON”(See Fig 8-1), the
system will perform a defrost cycle in any of the following
conditions:
1. If the compressor is operating and T3 is < 32 °F, the
system will perform a defrost cycle every 30 minutes of
operation.
2. If the compressor is operating and T4 is < 37.4 °F, the
system will perform a defrost cycle every 30 minutes of
operation.
3.When T3 is < 28.4 °F and the compressor is operating
for the first time after being connected power,the system
will perform a defrost after 15 minutes for the first time.
4. When T3 is < 28.4 °F and the system has been in
standby for two hours, the system will perform a defrost
after 15 minutes for the first time.
SW3
Switch
Fig.8-1 SW3 Switch Location in the PCB Board
(For reference only)
MANUAL DEFROST
AUTOMATIC DEFROST
NORMAL DEFROST
DEFROSTING CYCLE:30MIN
DEFROSTING CYCLE:60MIN
RESERVED
SW3-1
SW3-2
SW3-3
*
*
*
ON
OFF
ON
OFF
ON
OFF
1 2
ON
3
SW3
When SW3-1 switch is set to “OFF”(See in Fig 11), the
system will perform a defrost cycle in any of the following
conditions:
1. If the compressor is operating and T3 is < 32 °F, the
system will perform a defrost cycle every 60 minutes of
operation.
2. If the compressor is operating and T4 is < 37.4 °F, the
system will perform a defrost cycle every 60 minutes of
operation.
3.When T3 is < 28.4 °F and the compressor is operating
for the first time after being connected power,the system
will perform a defrost after 15 minutes for the first time.
4. When T3 is < 28.4 °F and the system has been in
standby for two hours ,the system will perform a defrost
after 15 minutes for the first time.
Shut-down conditions of defrost mode:
No matter what defrost mode is selected, the defrost
cycle will end in any of the following conditions:
1. The defrost cycle has been running for 10 minutes;
2. T3 is ≥ 64.4°F for more than 60s;
3. The compressor stops operating.
Table 8-1: Thermostat Signals
Table 8-2: Thermostat Wire Color
Signal
State
Board Function
G
Blower instant ON
Blower 90 sec. delay OFF
Blower instant ON
Heater bank 1 elec.onstant ON
Heater bank 1 elec.instant OFF
Blower 90 sec. delay OFF
Blower instant ON
Heater 1 instant ON
Heater 2 instant ON
Blower 90 sec. delay OFF
Heater 1 instant OFF
Heater 2 instant OFF
Blower instant ON
Compressor and outdoor fan instant ON
Compressor and outdoor fan instant OFF
Blower fan delay 90 sec. OFF
4-way valve instant ON
Blower instant ON
Compressor and outdoor fan instant ON
Compressor and outdoor fan instant OFF
Blower fan delay 90 sec. OFF
4-way valve instant OFF
4-way valve instant ON
Blower instant ON
Compressor and outdoor fan instant ON
Heater 1 instant ON
4-way valve instant OFF
Blower fan delay 90 sec. OFF
Compressor and outdoor fan instant OFF
Heater 1 instant OFF
4-way valve instant ON
Blower instant ON
Compressor and outdoor fan instant ON
Heater 1 instant ON
Heater 2 instant ON
4-way valve instant OFF
Blower fan delay 90 sec. OFF
Compressor and outdoor fan instant OFF
Heater 1 instant OFF
Heater 2 instant OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
ON
OFF
G & W1
G & Y
G & W & W2
G & B & Y
G & B & Y
& W1
G & B & Y
& W1 & W2
Thermostat Wire Color
Function
Red
Black
White
Green
Yellow
Blue
White/Black
Power wire
Power wire
Heater signal 1
Blower fan signal
Compressor signal
Reversing valve signal
Heater signal 2
21
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