Safety: Isolate power before working on the fan. Do not run the furnace with the fan disconnected.

Check for obstructions: Remove the upper front panel to access the flue fan (exhaust fan). Spin the fan wheel gently by hand with power OFF. It should rotate freely without scraping. Remove any debris or insect nests from the housing.
Inspect wiring: Check the plug connection from the fan to the control board. Look for discoloration, melted plastic, or loose pins. Reseat the connector.
Listen for fan start: Restore power and call for heat. If the fan hums but does not spin, the motor may be seized or the capacitor (on some models) may be faulty.
Measure voltage (qualified persons only): With appropriate tools and training, verify that the control board is sending mains voltage to the fan when a heat demand is present. If voltage is present but the fan does not run, replace the fan assembly.

Because the fan is part of the flue safety system, replacement should be carried out by an Ariston-authorized technician.

Furnace displays error 201, combustion fan does not start, no ignition attempt.

Possible Causes