Thermostat shows E9 and fan or compressor runs unexpectedly or not at all

Safety first: Turn off power to the HVAC system at the breaker before working on wiring.

• Step 1 – Observe behavior: Note whether the indoor fan, heat, or cooling runs continuously even when the thermostat is set to OFF. This helps identify which output is affected.
• Step 2 – Inspect thermostat wiring: Remove the thermostat and inspect the sub-base. Ensure there are no jumpers installed that should not be there (for example, R to Y or R to W unless specified by Amana wiring diagrams).
• Step 3 – Isolate thermostat: With power off, remove all wires from the thermostat sub-base except R and C. Restore power. If the equipment still runs or E9 persists, the issue is likely at the Amana control board or wiring, not the thermostat.
• Step 4 – Test with manual jumpers (advanced): At the furnace/air handler control board, briefly jumper R to G (fan), R to Y (cool), and R to W (heat) to verify each function operates correctly. Remove jumpers after testing.
• Step 5 – Replace thermostat: If the system behaves normally when controlled directly at the control board but E9 appears and outputs misbehave when the thermostat is connected, replace the Amana smart thermostat.

When to call a professional: If outputs are stuck on even with thermostat wires removed, the Amana control board relays are likely failed and require professional replacement.