Checking the flame detector
The gas dryer blows air through the burner to heat it. The burner assembly consists mainly of a gas valve, an ignition switch and, in dryers using an incandescent ignition, a flame sensor. If the flame sensor fails, the igniter may not ignite and gas flow may not start.
The easiest way to diagnose a flame sensor is to observe the operation of the burner. Remove the small front panel (if option is available, if not then the front of the dryer panel will need to be removed. Check out our video on YouTube https://www.youtube.com/watch?v=ZmA-n72D2yk ) select highest temperature and start the dryer. Observe the burner, the switch should begin to glow shortly after starting the dryer. If it comes on for a few seconds (up to 15 seconds) and then goes off, the problem is probably the solenoids (coils). If the igniter burns and stays on after the flame has been started, the problem is usually the flame sensor.
For testing purposes, flame sensor will read resistance at room temperature and no resistance when heated by ignitor.