5 red flashes, 3 green flashes — Communication error to main control

What does 53 mean?

The outdoor control has lost communication with the inverter. The compressor demands will stop, and the indoor blower will also stop functioning. This can happen if power is not cycled correctly during service.

• Outdoor control lost communication with inverter
• Power interruption during service
• Loose electrical connections

Click steps to track your progress.

1. 1

   Check for any loose or disconnected electrical connections.

2. 2

   Ensure consistent power to both indoor and outdoor units during service.

3. 3

   To clear a critical lockout: cycle outdoor unit power off and on, then cycle indoor unit power (24VAC to Lennox outdoor control) off and on.