Dryer Is Not Heating

If a dryer vent restriction is completely eliminated, and no heat is being produced, then you must diagnose the problem. When a dryer is not heating, there is a good possibility that the component that does the most work, the heater, is the problem. If you inspect the heater and find out that the resistance wire within the heater is broken, then you have found the problem. Remember in order for that heater to fail, it would have to have the full voltage to it. So don't make it more complicated and suspect that the timer is defective, or anything like that. It is possible though, that the control thermostat is stuck and the heater has been cycling on the high limit thermostat. But you will not be able to interpret that until after the heater has been replaced. There's no sense in checking the contacts of the control thermostat because we know that they are closed. We know this because in order for the heater to fail, the control thermostat contacts must be intact to allow voltage to be applied to the heater.

If there is no obvious break in the heater resistance coil, it may still be defective. The next thing that you should do is isolate the heater by removing one of the terminals supplying voltage to the heater. If you are unsure of your ability, you can remove both terminals that supply voltage to the heater. Now you can use an ohmmeter to check the resistance of the heater. A good dryer heater will show a resistance in the range of 5 to 30 ohms. If you are using a digital meter, (by the way we recommend that you use a digital multimeter), touch the two leads together so that you can see what happens when your meter reads zero resistance.

Notice when you touch the two leads together, the meter display goes down to zero, indicating zero resistance. When you separate the two leads from the meter, observe the display to see what happens. Most of the time it will just blink, depending on the brand multimeter that you have. When you place your multimeter leads on the heater terminal, if the heater is open, in other words broken in some place that is not obvious, the meter will continue to blink. This means that the heater must be replaced.

Sometimes when you get to the dryer heating element to inspect it, you'll find that one of the wires supplying voltage to the heater has burned in half. If you find a wire lead to a heater burned in half, you do not have to check the heater. In order for that wire to fail, the heater would have to be producing heat, and current would have to be passing through the wire. Of course you will have to repair the wire, but you should look for a vent restriction, or other condition that is causing the dryer to get too hot. This is actually a common problem with dryers that have the heater located behind the drum, such as Frigidaire and GE dryers. The problem happens when the customer opens the door to remove the clothing before the end of the cycle. When this happens the heater is on full blast, and has not had a chance to go through the cool down cycle. The heat from the heater radiates up to the wire terminals and sometimes causes them to deteriorate, or get brittle.

If you find that the dryer heater is good and the wires going to the heater are not defective, then you should check the dryer control thermostat and the high limit thermostat, sometimes called the safety thermostat, or fuse link. Once again, with your meter set to read ohms, remove the wires to the thermostat and check them for continuity. Unlike the heater, when you read resistance across a thermostat, it will show zero resistance. If the meter blinks indicating infinite resistance, then that thermostat is defective. All Dryer control and high limit thermostats will have normally closed contacts. If you find that a high limit thermostat or safety thermostat is defective, you need to check for a dryer vent restriction. If all the high limit thermostats and safety thermostats are good then you must go to the next thing in the circuit. Making sure that the heater is now reconnected, and all the wires to the dryer thermostats are connected, the next thing in the heater circuit is the heater switch contacts on the centrifugal switch, attached to the motor. The centrifugal switch on the motor is designed to close a set of contacts allowing current to flow to the heater, when the motor comes up to speed. The easiest way to check these contacts is to use a jumper wire with alligator clips. Connect the jumper wire across the wires in the heater circuit on the centrifugal switch. It is not necessary to remove them from the switch. Make sure that the dryer timer, and the temperature selector switch is set for heat. Now attach the leads from your digital multimeter, making sure that it is set to read ohms, to the left and right blades on the dryer cord. Some dryer cords are three conductor, and some are four. Either way, put your meter leads on the far left and right blades. If you read the resistance of the heater now, then you know that the dryer motor centrifugal switch is defective. If the meter still blinks infinity, do not remove the jumper wire from the motor centrifugal switch. We will leave it there to simulate that the motor is up to speed so that we can check the selector switch heat contacts, and the timer.

At this point, you will have to read the schematic diagram, and or the timer / electronic control sequence chart, for your particular model dryer. If a timer or electronic control sequence chart is not available, you will have to look at the wires attached to these items and follow them back. A dryer electronic control will either have a heavy duty relay on it, or have a separate heat control board with the relay on it. Either way, look for the heavy duty wires that run in and out of a relay. You can use an additional jumper wire across those contacts, again there is no need to disconnect them, to read resistance on your meter attached to the dryer cord. If you see resistance on the cord now, then you know that the relay was probably not closing.

You can check the heat selector switch, and the timer the exact same way. If at this point you still do not read resistance on your meter, it's time to throw in the towel and call a professional appliance service technician. The reason for calling in a professional at this point is that electronic control boards and timers are very expensive. If you guess what the problem is, and you are wrong, you'll be out the cost of that item. That's because electronic control boards and timers cannot be returned. One more thing, for the record, appliance service technicians do not like to work on appliances that have been taken apart by an inexperienced person. Make sure that you put the dryer completely back together before you call a dryer technician. This will save you the expense of having them put it back together for you.