Troubleshooting gas valves includes checking for coil burnout, failure to open, failure to close and valve noise. Other steps involve checking the connection to the valve, direction of the pilot flame and adjustment of the screw to the pilot frame.
The first step to troubleshooting a gas valve is seeing if the coil has burned out. Signs of a burned out coil include the coil running over or under its normal voltage level. The coil housing and plate, enclosing tube, sleeves and plunger should be checked at the same time.
Sometimes, gas valves don't open or close properly, so that's the next step in troubleshooting. If the valve is filled with drudge, it has to be removed and cleaned. If the valve doesn't close properly, a faulty electrical circuit is the likely culprit. The faulty switch or relays need to be replaced.
Valves that are partly opened or closed make noise. This is usually a sign of one of the above and should be handled appropriately.
Next, the valve must connect properly to its thermocouple. If not, the threads need to be cleaned. The pilot flame needs to be aimed so it heats the top portion of the thermocouple. If not, the pilot screw requires adjustment. This is also the case if the flame goes out too quickly.