The burner assembly uses a circuit with a flame sensor to ignite the burner. When the dryer starts to warm up, the circuit through those components starts to warm up. The igniter glows until it reaches the proper temperature to ignite the gas, at which point the flame sensor opens and the current flowing through that circuit is diverted to the gas valve coil so the gas valves open, and the burner lights and continues to burn. The gas valves will not open if the coil fails. The burner lights during the initial ignition sequence from a cold start, but it fails to light the burner on subsequent attempts if the gas valve coil is weak. You should replace the valve coil in this situation.
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