Upon inspection, the unit was not operational. I checked the system and discovered a lack of 24 volts reaching the W wire. By temporarily bypassing the unit, I identified multiple issues during the heating cycle. The furnace module repeatedly clicked the igniter, and the gas valve opened and closed continuously. Removing power from the W wire caused the inducer motor to run indefinitely until I tapped the relay. I found a 5-amp fuse wrapped in aluminum tape, which was completely melted. Burn marks on the connections confirmed a short circuit. I recommended a replacement due to likely compromised parts and the unit's age. I emailed the customer replacement estimates and turned off the power at the breaker.
