Error Code: EH 3b – External Fan DC Bus Voltage is Too High Fault

Error Code: EH 3b – External Fan DC Bus Voltage is Too High Fault

What this means:
The indoor unit is receiving either abnormally high voltage feedback or no feedback at all for over 150 secondsfrom the external fan module. This indicates a fault in communication or voltage regulation between the indoor PCB and external fan driverTS35.

Try this first (quick reset):

1. Turn off the system power.

2. Wait at least 2 minutes.

3. Turn the unit back on and observe the display.

• If the error clears — operation resumes normally.

• If the error returns — proceed with diagnostics.

Next steps (for technicians):

1. Check ENC1 configuration:

   • If incorrectly set → reset ENC1 to factory defaults.

2. If ENC1 is correct and fault persists:

   • Replace the indoor main PCB.

What you might need:

• Indoor main PCB

Helpful tip:
EH 3b is part of a group of external fan voltage errors along with EH 3A and EH bA. All rely on accurate DC feedback from the external fan module. Start with configuration checks before replacing parts.

Click here to view the detailed guide.TS35