Panasonic water heater shows H03 and shuts down; fan may not start or runs briefly then stops.

Safety: Disconnect power at the breaker before opening the unit. Do not insert fingers or tools into the fan while power is connected.

• 1. Listen for fan operation: When starting hot water, you should hear the fan ramp up. If it is silent or just hums, suspect a fan issue.
• 2. Inspect air intake and exhaust:
  • Check for obstructions at the intake grill and exhaust terminal.
  • Remove leaves, nests, or debris that could jam the fan.
• 3. Access the combustion fan (qualified persons):
  • Remove the front cover.
  • Locate the combustion fan assembly near the flue connection.
  • Check if the fan wheel spins freely by hand (with power OFF). If stiff or jammed, the motor or wheel is faulty.
• 4. Check wiring:
  • Inspect the fan motor connector and harness to the PCB for loose or burnt pins.
  • Reseat connectors securely.
• 5. Clean dust buildup: Use a soft brush and vacuum to remove dust from the fan blades and housing, avoiding bending the blades.
• 6. If H03 persists: Replace the combustion fan motor assembly. This typically requires disassembling the flue connection and should be done by an authorized Panasonic technician.