Dehumidifier shows E9 and will not start or shuts down unexpectedly.

Safety first: Unplug the unit before opening any panels.

Steps:

• 1. Hard reset: Unplug the dehumidifier for at least 10 minutes to allow capacitors to discharge. Plug it back in and see if E9 clears.
• 2. Inspect power quality: Ensure the unit is plugged directly into a properly grounded outlet, not a long extension cord or power strip. Voltage drops and surges can corrupt memory.
• 3. Check board connections: Remove the control panel cover and verify that all harnesses to the main control board are fully seated. Look for signs of arcing or burnt traces.
• 4. Surge protection: If E9 occurred after a storm or power event, consider using a surge protector once the unit is repaired or replaced.
• 5. Replace main control board: If E9 persists after reset and connector checks, the EEPROM or microcontroller on the main board is likely damaged. Replace the board with the correct Carrier part number.

Note: Control board replacement involves handling static-sensitive components; use proper ESD precautions or have a technician perform the repair.