Error Code: EC 5C – Pressure Sensor Failure

Error Code: EC 5C – Pressure Sensor Failure

What this means:
The system has detected that the pressure sensor voltage is out of the normal range. Specifically, if the sensor output is below 0.5V or above acceptable limits, the system will shut down and display EC 5C to prevent incorrect pressure regulation.

Try this first (quick reset):

1. Turn off the power completely.

2. Wait 2 full minutes.

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

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

• If it returns — proceed with the diagnostics below.

Next steps (for technicians):

1. Check the wiring between the pressure sensor and the outdoor PCB:

   • Ensure all connections are secure and properly seated.

   • If miswired or loose → repair or reconnect.

2. Measure the voltage between pin 1 and pin 2 of the pressure sensor:

   • If the voltage is below 0.5V or exceeds 254V → replace the pressure sensor.

3. If the sensor and wiring are normal but the issue remains:

   • Replace the outdoor PCB.

What you might need:

• Pressure sensor

• Outdoor PCB

• Connection wires

Helpful tip:
Voltage anomalies at the sensor pins are the most reliable indicator for this fault. Always test voltage before replacing components.

Click here to view the detailed guide.TS43