Gas Dryer Not Heating

Troubleshooting a gas dryer can be rather tricky. In fact it's not uncommon for Appliance Service Technicians to say, "I don't work on gas dryers." Usually when a technician says this, he is calculating the estimated profit on the repair, versus the potential liability. That's why good experienced appliance service technicians, love to work on gas dryers. The fact is if you know what you're doing, the risk is relatively low. Gas dryers have several built-in safeguards, to prevent gas from flowing to the burner when it's not supposed to.

Almost all gas dryers manufactured today, operate using the same burner control systems. In fact most appliance manufacturers get all of their gas dryer burner parts, from one or two suppliers. Therefore a gas dryer coil set for a Frigidaire dryer, in most cases is the same as the gas dryer burner coils on a Maytag or Whirlpool dryer.

When the timer or electronic control, and the control thermostat, or thermistor is satisfied, power is applied to the igniter through the primary coils, and it starts to glow red. The heat from the igniter heats the flame sensor to a point that is sufficient for gas to ignite. The current passing through the primary coils creates an electromagnetic field lifting up a plunger inside the gas valve, and allows gas to flow to the secondary portion of the gas valve. At this point no gas is coming out of the valve. The heat from the igniter flexes a bimetal in the sensor opening the circuit to the igniter. Because electricity always takes the path of least resistance, if it has a choice to go through the low resistance igniter, or the higher resistance coils, it will always choose the igniter. Once the bimetal flexes and takes the path out of the circuit through the igniter, current will then flow through the secondary coil on the coil kit. When that happens the coil creates an electromagnetic field, lifting up a plunger on the gas valve, that has up until this point been preventing the gas from flowing into the burner. And since the ignitor is still red hot, because it hasn't had time to cool down, once the gas starts flowing it will ignite. The heat from the gas burner will keep the bimetal in the flame switch flexed, keeping the contacts close, allowing current to flow through the secondary coil on the gas valve, allowing gas to continue to flow.

Under normal conditions the control thermostat, or electronic control cycles off interrupting the circuit to the gas burner assembly causing the coils to lose their electromagnetic fields shutting down the gas flow. Once the control thermostat cools back down and closes the contacts within it, or when the electronic control energizes the heat relay, power is once again applied to the ignitor, to start the sequence over again.