Thermostat shows E15 and cannot control first-stage heating (W1)

Safety first: Turn off power to the furnace/air handler at the breaker before working on wiring.

• Step 1 – Inspect W1 wiring at thermostat: Remove the thermostat and verify the W1 wire is properly clamped and not damaged.
• Step 2 – Inspect W1 wiring at furnace: At the Amana control board, confirm the W or W1 terminal has the correct conductor attached and that the connection is tight.
• Step 3 – Check low-voltage fuse: Inspect and replace the control board fuse if blown. If it blows again, inspect the W1 wiring for shorts to ground or other conductors.
• Step 4 – Bypass thermostat (advanced): With power on, briefly jumper R to W at the Amana control board. If the furnace starts a heat cycle, the thermostat or W1 wire is faulty. If not, the furnace control or safety circuit is at fault.

When to call a professional: If the furnace does not respond to an R-W jumper, an HVAC technician should diagnose the Amana furnace ignition and safety circuits.