Moffat Dryer Error Code F3

The F3 error code on a Moffat dryer indicates that the appliance was unable to reach the selected humidity end level within the allotted drying cycle time. As a protective measure, the dryer automatically shuts down after 3 hours of operation when the target humidity level cannot be achieved. This code points specifically to a failure in the humidity sensing system, which is responsible for monitoring moisture levels in the drum and signaling the electronic control board when laundry has reached the desired dryness level.

The humidity sensor is a critical component in automatic drying cycles. It typically consists of two metal sensing bars inside the drum that detect electrical conductivity as wet laundry passes across them. As clothes dry, conductivity decreases, allowing the control board to calculate remaining moisture content. If the sensor itself is faulty or the wiring connection between the sensor and the electronic control is broken, corroded, or intermittent, the control board cannot receive accurate humidity data and the dryer will run indefinitely until the 3-hour safety cutoff triggers.

Diagnostic work should begin with a visual inspection of the humidity sensor bars for residue buildup, damage, or corrosion, followed by checking all wiring harness connections between the sensor and the electronic control board. A faulty sensor may produce out-of-range resistance readings when tested with a multimeter. If the connections are intact and the sensor tests within specification, the fault may lie in the electronic control board itself, which processes the sensor signal.