ELECTRIC DRYER WON'T HEAT
HI. There are a few areas i would advise to check to resolve this issue.
The dryer uses multiple thermostats to regulate the temperature. When the temperature is higher than the preset limit of a particular thermostat, the thermostat breaks the circuit and the heater goes off. When the temperature cools enough, the thermostat closes the circuit again and the heat can come on.
Most dryers have a choice of temperature settings, therefore a separate thermostat is used for each setting. The selector switch or timer control then routes the circuit through the appropriate thermostat.
If a thermostat fails, it may prevent the heat from coming on, or cuase long drying periods This happens because the thermostat does not close the circuit when the temperature falls below the operating temperature of the switch. It is a simple matter to test a thermostat; it should show continuity when the switch is cool and no continuity when it is warmer than its rated temperature.
A thermostat can also fail by being always on, no matter what the temperature. This switch would show continuity whether it was hot or cold. In this case, the heater will not shut off and the the dryer could dangerously overheat. As a safety precaution a second thermostat is used, This is called a thermal fuse. The power will be cut to the heating circuit if the maximum safe temperature is exceeded. In most cases, this is a one time fuse and the entire unit will not be able to operate correctly. The heater circuit, or entire unit, will not function until the fuse has been replaced. Of course, it will be necessary to determine and repair the underlying cause of overheating or the fuse will just cut out again. The most common cause of overheating and long drying periods, will be a clogged ventilation assembly. Be sure to inspect the entire ventilation Assembly for build up. This will cause issues, if obstructions exist.
The thermostats are usually grouped together. The are typically oval in shape and about an inch and a half in size. They may be on the blower housing, under the lint trap or inside the vent line. There should be two wires connected to each thermostat.
Label the wires and connections so that you can properly reconnect them later. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals. You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If either is corroded they should be cleaned or replaced.
To test the thermostats or fuse, set the multimeter to the ohms setting X1. Touch one probe to each terminal. You should get a reading of either zero or infinity. At room temperature, the thermostats should have a reading of zero. When the thermostats are heated to their limit temperature, they should switch off and you should get a reading of infinity. The fuse should be tested at room temperature for continuity.
NOTE(If the Thermostats and fuse check out ok, replace the element. Element failure is uncommon but, it may fail in certain cases))
Jan 11, 2010 |