Error Code: EC 53 – Outdoor Ambient Temperature Sensor (T4) Error

Error Code: EC 53 – Outdoor Ambient Temperature Sensor (T4) Error

What this means:
The T4 sensor, which measures the outdoor air temperature, is either disconnected, shorted, or reading abnormally. This can disrupt system performance and trigger a shutdown.

Try this first (quick reset):

1. Turn off power to the system completely.

2. Wait 2 full minutes.

3. Turn the system back on and check the display.

• If the error clears — it may have been a temporary fault.

• If it returns — continue with the checks below.

Next steps (for technicians):

1. Check wiring:

   • Make sure the T4 sensor is properly connected to the outdoor PCB.

   • Repair or replace loose, corroded, or damaged wires.

2. Measure sensor resistance:

   • If resistance is outside the normal range → replace the T4 sensor.

   • If resistance is normal and wiring is fine → proceed.

3. If issue remains:

   • Replace the outdoor main PCB.

What you might need:

• T4 ambient temperature sensor

• Outdoor main PCB

• Connection wires

Helpful tip:
In some models, T3, T4, and TP are part of the same combination sensor. Always confirm your unit’s sensor configuration before ordering replacement parts. This error is triggered when the sensor’s voltage drops below 0.06V or rises above 4.94V.

Click here to view the detailed guide.TS05-ODU