Flame Sensor
Flame rectification, microamp readings and cleaning.
Furnace Blowing Cold Air: A Diagnostic Order That Finds It Fast
Why a gas furnace blows cold or lukewarm air, in the order to check it: thermostat fan setting, lockouts, flame proving, limits, gas supply, and duct leaks.
Furnace Flame Sensor: Microamp Readings, Cleaning and When to Replace
How flame rectification works, how to measure flame sensor microamps, what readings are normal, and how to fix weak flame signal.
Furnace Ignition Lockout: Failed Ignition Troubleshooting Step by Step
Diagnose a furnace that tries to light and locks out by following the ignition sequence: inducer, pressure switch, igniter, gas valve, flame sense.
Furnace Short Cycling: 7 Causes and How to Pin Down Which One
Diagnose a gas furnace that lights and shuts off too soon, from flame sensing and limit trips to oversizing and thermostat settings.