If a two-year-old gas furnace locks out while attempting to light, what has the technician determined when reading 19 VAC at the gas valve?

When a technician measures 19 VAC at the gas valve during a lockout situation, it indicates that there is inadequate voltage being supplied to the gas valve. Gas valves typically require a standard voltage level, often around 24 VAC, for proper operation. If the voltage reading is significantly lower, as in this case with 19 VAC, it suggests that there may be an issue with the electronic control board that regulates the voltage to the gas valve.

A faulty electronic board can cause various operational issues in a furnace, including improper voltage distribution, which can prevent the gas valve from opening correctly. This situation leads to a lockout condition as the furnace is unable to ignite due to insufficient voltage.

Understanding this behavior helps technicians identify the underlying issue promptly, allowing for appropriate troubleshooting and repairs. Other potential problems, such as a faulty gas valve, improper venting, or thermometer malfunctions, would not directly cause this specific voltage reading at the gas valve. Thus, the correct determination is that the electronic board is likely faulty due to the low voltage observed.