Tempstar air conditioner indoor display shows E9 and unit will not operate

Safety first: Turn OFF power to the indoor unit at the breaker.

Steps:

• 1. Power reset: Leave power off for at least 10 minutes to allow capacitors to discharge and the board to fully reset. Then restore power and check if E9 clears.
• 2. Check for surge protection: If the error appeared after a storm or outage, the board may have been damaged by a surge. Inspect for burn marks or swollen components on the board (do not touch circuitry).
• 3. Verify correct board: If the board was recently replaced, confirm the part number matches the Tempstar model and that any required dip switch or jumper settings are correct.
• 4. If E9 persists: The control board will likely need replacement. This involves transferring all wiring correctly and should be done by a technician following Tempstar wiring diagrams.