Heater display shows E03 and the compressor does not start

Critical safety warning: Refrigerant systems are pressurized and must only be opened by certified refrigeration technicians. Do not attempt to cut or open refrigerant lines.

• Check ambient conditions: Confirm that outdoor temperature is within the operating range specified by BWT for your model. Very low temperatures can trigger low-pressure protection.
• Inspect evaporator coil: With power off, remove the front or side panel to view the evaporator (air coil). Clean off leaves, dust, and debris with a soft brush and low-pressure water spray, avoiding bending fins.
• Check airflow: Ensure nothing is blocking the air inlet or outlet of the heater. Maintain the clearance distances recommended by BWT.
• Visual leak check: Look for oily residue on refrigerant piping, joints, and around the compressor, which can indicate a leak. If found, stop using the heater and call a refrigeration technician.
• Reset power: After cleaning and ensuring proper airflow, restore power and restart the heater to see if E03 clears.

If E03 persists, a low-pressure switch or refrigerant charge issue is likely. Contact a qualified refrigeration technician to test the low-pressure switch and check refrigerant levels.