Thermostat displays E11 and indicates fan control error; indoor blower may run continuously or not at all

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

Steps to troubleshoot E11 fan output fault:

• 1. Inspect thermostat wiring: Confirm the green G wire is properly connected at the thermostat and at the Goodman control board G terminal. Look for signs of pinched or damaged insulation.
• 2. Isolate thermostat: Disconnect the G wire at the thermostat and furnace control board. Use a multimeter to check for continuity to ground or other conductors; any short must be repaired by replacing or rerouting the cable.
• 3. Test blower relay: With power on and the thermostat calling for fan ON, measure 24VAC between G and C at the furnace control board. If voltage is present but the blower does not run, the blower relay or motor is suspect (beyond thermostat scope).
• 4. Bypass thermostat: Temporarily jumper R to G at the furnace control board. If the blower runs normally, the thermostat G output may be defective.
• 5. Replace thermostat if needed: If wiring is good and the blower responds to a manual jumper but not to the thermostat, replace the thermostat.