My fisher & paykel gas dryer is not heating up
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, 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 would 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. The heater circuit 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 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.
Ok, once you have ruled out any thermostat and fuse issues, and the venting is not clogged, this will lead to the valve assembly.
On the gas valve are one or two coils (solenoids) used to open and close the valve to control the flow of gas. If a coil fails, gas will not flow and the dryer will have no heat.
The easiest way to diagnose a problem in the burner assembly is to observe the burner operation. Remove the small access panel at the bottom, front of the dryer, select a high temperature setting and start the appliance. Watch the burner assembly, shortly after starting the dryer the ignitor should begin to glow. Next you should hear the click of the gas valve coil and a flame should ignite. The flame should be mostly blue and it should remain on for a minute or more.
If the ignitor glows for several seconds (up to 15 seconds) and then goes out, the problem is probably the coils (solenoids). If the ignitor glows and stays on, then the problem is usually the flame sensor. If it ignites and then quickly goes out, it is most likely a problem with inadequate air flow.Test the coil for resistance using a multimeter. Set the multimeter to the ohms setting X10. Place a probe on each terminal. The multimeter should change from a reading of infinity to roughly 1300 ohms (+/- 150 ohms) when the probes touch the terminals. If the reading is infinity or substantially different from 1300 ohms, the solenoid should be replaced.
Additionally, i would inspect the ignitor as well.
The easiest way to check the ignitor is to observe it. Remove the small access panel in front, select a high temperature setting and start the dryer. Watch the burner assembly, shortly after starting the unit the ignitor should begin to glow or spark. If you see it glow or spark, then the ignitor is working. If the ignitor did not appear to function and it is the spark type, it may be out of adjustment which generally requires professional service or it may require replacement. If the ignitor is the glow type, you can test it for resistance with a multimeter.
The ignitor has two wires connected to it.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 (do not pull on the wire itself). 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.
Set the multimeter to the ohms setting X1. Touch one probe to each terminal. You should get a reading anywhere between 50 and 600 ohms. If you get a reading of zero or infinity, the ignitor is definitely bad and will need to be replaced.
on Mar 06, 2011