Lennox HARMONY III Error Codes

Zone controller

Model numbers in this family: HARMONY III, X9953

• 0000 Normal operation
• 0001 Simultaneous heat and cool call from same thermostat
• 0010 Defrost while gas heat selected
• 0011 Multiple jumper selection
• 0100 Defrost time > 20 minutes
• 0101 Insufficient heating
• 0110 Zone air jumper not selected
• 0111 Dual-fuel furnace use lock-in
• 1000 Insufficient cooling
• 1001 Open pressure switch (heat pump systems only)
• 1010 Discharge Air Sensor (DAS) detects high heating temperature
• 1100 Unsteady thermostat input
• 1101 DAS sensed frozen coil
• 1110 Open or shorted DAS

Reference only. Confirm against the manual for your exact model. Data release 105f66ecb9e96e5dc473025d.