Lennox HP13 Heat Pump Re: Diagnostic Codes / Fault Codes The defrost board uses two LEDs for diagnostics. The LEDs flash a specific sequence according to the condition. DIAGNOSTIC CODES: Green Red Description Off Off No Power to Control Simultaneous Slow Normal...

Lennox XP13 Heat Pump: Heating Re: High Pressure Fault/Lockout There are two different High Pressure Indications: A High Pressure Fault occurs when the Hi Pressure Switch opens and is indicated by a Slow Flashing Green LED on the outdoor unit control board. A High Pressure Lockout occurs after...