General Air Conditioning | Technical Reference
ARTC72LATU / ARTC90LATU External Input & Output
Remote operation, status monitoring, fresh-air control and auxiliary-heater integration
Electrical safety: Isolate the indoor unit before connecting or removing any harness. External loads must be switched through a correctly rated field-supplied relay. Do not connect mains voltage directly to low-voltage PCB terminals.
1. External Input & Output Summary
| Function | Type | Connector | Typical Use |
|---|---|---|---|
| Control input (Operation/Stop) | Input | CN103 | Remote switch or BMS start/stop |
| Operation status | Output | CN100 | Run indication or BMS monitoring |
| Error status | Output | CN101 | Fault alarm or external indicator |
| Fresh air control | Output | CN161 | External ventilation fan relay |
| Auxiliary heater | Output | CN160 | External electric heater relay |
2. Control Input — Operation / Stop
A field-supplied, non-polar contact can remotely start or stop the indoor unit through CN103.
| Item | Requirement |
|---|---|
| Connector | CN103 |
| Contact capacity | 5 V DC or more, 15 mA or more |
| Switch type | Non-polar relay or dry contact |
| Maximum cable length | 10 m |
| Optional harness | UTD-ECS5A |
Initial start after power is applied
| Parameter | Initial Start | Later Starts |
|---|---|---|
| Operation mode | Auto changeover | Previous mode |
| Set temperature | 24 °C | Previous set temperature |
| Airflow | Auto | Previous airflow setting |
Signal logic: Contact ON = unit operates. Contact OFF = unit stops.
3. Operation and Error Status Outputs
| Output | Connector | Electrical Limit | Signal Logic |
|---|---|---|---|
| Operation status | CN100 | 24 V DC maximum; relay load 10 mA to less than 500 mA | Operating = ON; stopped = OFF |
| Error status | CN101 | 24 V DC maximum; relay load 10 mA to less than 500 mA | Error = ON; normal = OFF |
Important: The output is intended to energise a compatible relay coil or low-voltage monitoring input. Keep the PCB-to-connected-device cable run within 10 m.
4. Fresh Air Control Output
The CN161 output follows indoor fan operation and can be used to energise a field-supplied relay controlling an external fresh-air fan.
| Output voltage | 12 V DC |
| Relay rating | 12 V DC, 50 mA or less |
| Cable length | 10 m maximum |
| Optional harness | UTD-ECS5A |
| Signal behaviour | Indoor fan ON = output ON; indoor fan OFF = output OFF |
Cold-air prevention: The fresh-air output switches OFF while the indoor unit is in cold-air prevention control during heating.
5. Auxiliary Heater Output
The CN160 output is intended to control a field-supplied relay for an external duct heater. It is linked to heating operation, indoor fan operation and compressor operation.
| Output voltage | 12 V DC |
| Relay rating | 12 V DC, 50 mA or less |
| Cable length | 10 m maximum |
| Optional harness | UTD-ECS5A |
Operating logic
The output is ON while heating operation, the indoor fan and compressor are operating. It turns OFF as room temperature approaches the set temperature. The manual also notes that the output is turned OFF when room temperature is substantially different from the set temperature.
One-minute fan delay
The indoor fan can be configured to continue for approximately one minute after the heating thermostat turns OFF. This is enabled by cutting the applicable jumper wire on the indoor PCB.
Heater installation requirement: Install the external heater between the indoor unit and the ductwork. Confirm fan-delay operation so residual heat is safely removed after the heater output turns OFF.
6. Commissioning Checklist
| 1 | Confirm the correct connector and harness before energising the unit. |
| 2 | Verify relay coil voltage and current are within the stated PCB limits. |
| 3 | Insulate all unused conductors and secure wiring away from sharp edges and moving components. |
| 4 | Test remote start/stop, operation output and error output independently. |
| 5 | For fresh-air or heater applications, confirm the connected equipment stops under the required safety conditions. |
| 6 | Record connector use, relay details and functional test results in the commissioning report. |
Support: For wiring interpretation or application advice, contact Assist Technical Support on 1300 364 484 in Australia or +64 4 568 8761 in New Zealand.