Error Code: EC 50 – Outdoor Temperature Sensor Error (T3, T4, TP)

Error Code: EC 50 – Outdoor Temperature Sensor Error (T3, T4, TP)

What this means:
The system has detected that one or more outdoor temperature sensors — T3 (coil), T4 (ambient), or TP (discharge) — is either open circuit or short circuit. This causes the sensor voltage to fall outside of the safe range, and the system shuts down to avoid incorrect temperature control.

Voltage fault threshold:

• If sensor voltage is < 0.06V or > 4.94V, the system triggers EC 50.

Try this first (quick reset):

1. Turn off power to the system completely.

2. Wait 2 full minutes.

3. Turn it back on and check if the error clears.

• If the error clears — the issue may have been temporary.

• If the error returns — continue with the steps below.

Next steps (for technicians):

1. Check sensor wiring to the PCB:

   • Confirm all sensor connections (T3, T4, TP) are properly wired and securely connected.

   • If wiring is loose or damaged → repair or replace wires.

2. Measure resistance of each sensor:

   • If a sensor’s resistance is out of the normal range → replace the sensor.

   • If all sensors measure within spec → continue.

3. If all sensors and wiring are correct but error remains:

   • Replace the outdoor main PCB.

What you might need:

• T3, T4, or TP sensor (single or combination depending on model)

• Outdoor main PCB

• Connection wires

Helpful tip:
Some systems use a combo sensor for all three (T3, T4, TP). Always verify your model’s sensor configuration before ordering replacements.

Click here to view the detailed guide.TS18