Furnace displays E1 and will not respond to thermostat calls

Safety first: Switch OFF power to the furnace at the breaker and service switch before opening panels.

• Inspect thermostat cable: Remove the blower door and locate the thermostat wires on the Kelvinator control board (R, W, Y, G, C). Check for cuts, crushed insulation, or bare copper touching the cabinet.
• Bypass thermostat (test only): With power OFF, remove the W wire from the control board. Restore power and briefly jumper R to W at the control board using a short piece of insulated wire. If the furnace starts a heat cycle, the thermostat or thermostat cable is likely faulty. Remove the jumper after testing.
• Check thermostat settings: Ensure the thermostat is set to HEAT and the temperature is set above room temperature. Replace batteries if applicable.
• Tighten connections: Confirm all thermostat wires are firmly clamped under the terminal screws at both the thermostat and the furnace control board.
• Replace suspect parts: If the E1 code clears when jumpered at the furnace but not with the thermostat connected, replace the thermostat or run new thermostat cable.