Heil air conditioner displays E9; unit may run with poor performance or shut down

Safety first: Disconnect power at the breaker and outdoor disconnect before touching the control board.

• Step 1 – Power cycle: Turn off all power to the system for at least 10 minutes to allow capacitors to discharge and memory to reset. Restore power and check if E9 clears.
• Step 2 – Inspect board connections: Remove the control panel cover and gently press all multi-pin connectors into the board to ensure good contact.
• Step 3 – Check for surge damage: Look for burn marks, cracked components, or a burnt smell on the board. If present, the board must be replaced.
• Step 4 – Surge protection: Consider installing a surge protector on the Heil condenser to prevent future board failures.
• Step 5 – Board replacement: If E9 persists after reset and inspection, have a technician replace and program the correct Heil OEM control board.