In COOL mode, the unit operates to cool the room.  The temperature control range in cooling mode is 60°F - 86°F.


Indoor Unit


To enter the cool mode, point the infrared remote control at the indoor unit and press the power button., then press the COOL mode button if not already set to cool mode.

  1. The signals received by the infrared receiver are relayed to the main board of the indoor unit to turn the system on and set it to cool mode. The temperature set by the remote control and the indoor unit's ambient temperature sensor will determine if a call for cooling is needed.
  2. The indoor unit main board will activate the display of the indoor unit, illuminating the display, indicating the room temperature and current status of the unit.
  3. The indoor unit main board will signal the louver stepper motor to open the louver and the indoor fan will operate at the speed last set.
  4. As the louver opens, the indoor unit main board will power up the indoor fan motor, operating the fan at the speed last set.
  5. The indoor fan motor has a feedback circuit which provides the indoor unit main board with information for controlling the speed of the fan motor. The speed of the indoor fan can be controlled manually or automatically by the system.
    • Manual: The speed can be changed between LOW, MEDIUM, and HIGH. There will be a 2 second delay when manually controlling the speed.
    • Automatic: The automatic control adjusts according to room temperature, set temperature, current fan speed, or when the sensor is off.

Temperature Sensors


  • The indoor unit has two sensors that provide temperature information to the indoor unit main board. The sensors are used for controlling the system during cool mode.
  • The sensors are: an indoor ambient temperature sensor, and pipe temperature sensor.

Communication Between Indoor and Outdoor Units


  • The indoor and outdoor unit main boards communicate via a digital signal on the wire connected to terminal 3 of each unit. A splice or break in this wire will cause a communication error.
  • When a command is received from the remote control, the indoor unit main board communicates with the outdoor unit main board via the terminal 3 wire to perform the requested function.

Outdoor Unit

  1. Upon a request for cooling, the outdoor unit main board applies power to the outdoor fan motor and compressor.
  2. Depending on system cycling, there can be a delay of up to 3 minutes before the outdoor unit fan and compressor start.
  3. The outdoor unit temperature sensors used in conjunction with the indoor temperature sensors, indoor ambient and tube, provide information to the outdoor control board to monitor the system and regulate the frequency of the compressor, EEV positioning, and outdoor fan speed to achieve the desired room temperature.
  4. When cooling has been satisfied, the outdoor unit compressor will turn off, followed by the outdoor fan. The indoor unit fan will continue to run.


If the system detects a malfunction, it may shut down or show an error code on the indoor unit display board and/or outdoor unit main board LED.