Trane 4TXK6512G1000AA, Service Manual, Page: 155 / 187

8.3 Indoor unit function
1. Dry mode Operation
1) Tai < 16°C, indoor unit stops running and sends stop-unit signal to outdoor.
2) Tai>Tset+2°C, indoor unit runs at cooling mode and sends cooling -mode signal to outdoor
3) Tse<Tai≤Tset +2°C,indoor unit send DRY mode signal to outdoor unit
4) Tai≤Tse, indoor unit runs at low speed and sends stop-unit signal to outdoor.
2. auto mode:
1): If the unit enters Auto mode for the first time, the system will adjust the operation mode according to the
room
temp. and the set temp.
When Tai ≥ Tset, entering auto cooling mode;
When Tai<Tset, entering auto heating mode.
2):
Auto cooling mode is as the same as the cooling mode. After the thermostat is OFF for 15 minutes, or
the unit will still stay at auto cooling mode and stop when it reaches the set temperature;
3): Auto heating mode is as the same as the heating mode. After the thermostat is OFF for 15 minutes, if
Tai≥Tset+1 +Tdif, the unit will enter auto cooling mode, or the unit will still stay at auto heating mode;
4): In this mode, the Sleep function is available, run as cooling sleep in cooling mode and as heating sleep
in heating mode. Once sleep mode is set, the mode will not change after the unit stops for 15 minutes when it
arrives Tset.
3. Abnormal Operation
1): When outdoor modes from the request of indoor unit conflict, the one entering firstly will take priority.
2): After indoor receives the ON command from wired controller, it will firstly confirm the outdoor current
operation mode. If they are the same modes, indoor unit will run as the request of remote controller. If they are
different modes, the system will forbid to operate, and indoor will keep the OFF mode and send the “standby”
signal to wired controller until outdoor stops or outdoor mode the requested mode of wired controller are the same,
the unit will run as the requested mode of wired controller.
3): After indoor receives the ON command from remote controller, it will firstly confirm the outdoor current
operation mode. If they are the same mode, indoor unit will run as the request of remote controller. If they are
different modes, the system will forbid to operate, and indoor will keep the OFF mode. After setting on remote
controller, if the buzzer sounds two times, that shows abnormal operation. Indoor will run until the outdoor mode
and the requested mode of remote controller are the same.
4): COOL (included AUTO COOL), DRY, FAN are not abnormal mode.
4. Room Card Function
The unit adopts room card function (5VAC input), which only make ON/OFF control. When it is connected, the unit
is ON; when it is disconnected, the unit is OFF, and the other parameters will be as default or the data in memory.
A: When room card function is available
The central control, remote control/wired control and the room card are "AND" logical relationship. On the condition
that the room card is connected, the unit can be controlled by remote controller or wired controller; indoor unit will
run at the set state by the central controller, remote controller or wired controller; otherwise, if room card is not
connected, the unit cannot be controlled.
B: When room card function is not available, the unit will be controlled by the remote controller, the wired
controller or the central controller.