Common tumble dryer problems, faults and fixes

In order to facilitate any dryer troubleshooting, we will analyze the basic mode of operation of these appliances. There are essentially just 2 types of dryers, the vented dryer and the condenser type dryer. Whether they are powered by electricity or by gas, most commercial dryers fall into these 2 categories.

The vented dryer utilizes a vent to disperse hot air from the dryer to the outside. In most cases a venting hose is attached to the machine exhaust to allow it to release hot air outside the room where the machine is installed.

A self-condensing dryer allows water vapor to condense internally during the drying cycle. This water may then be expelled via a drainage mechanism. Water expelled from the dryer is either released into the home drainage system or is collected in a drum that must be emptied out physically.

For the most part, tumble dryer problems are fairly standardized and restricted to issues such as the dryer failing to heat up adequately. Following a simple step by step process can help you analyze and solve most tumble dryer faults effectively. Just opting to replace parts without justification is not the ideal way to troubleshoot these appliances. It is far better to understand the root causes of such problems so that you can prevent them from reoccurring.

In essence, a dryer requires adequate heat, ventilation (flow of air), and mechanical action if it is to perform at its peak. If any of these 3 factors are lacking, the dryer performance will suffer.

Troubleshooting the Heater elements and Thermostats

Most problems within the dryer tend to originate from the machine's heating unit or thermostat. Testing the functional capacity of the heater components can be relatively straightforward. Using an Ohm (electrical) meter will allow you to check the continuity of these parts and help pinpoint the origin of most tumble dryer problems. A heating unit that is open circuit should be discarded and replaced.

When there is no open circuit in the heater and continuity exists, you can turn your attention to the thermostats. Most dryers will have 1-2 thermostats mounted near the heater assembly, with the possibility of 2 more thermostats located in the vent. Vent thermostats are generally referred to as Exhaust stats are not normally known to fail. Checking this thermostat can be complicated as it will require the application of heat while the device's response is being monitored.

The thermostats mounted on the heater assembly are the cycling thermostat and the overheat thermostat, also called a Thermal Overload Cutout or TOC.

During regular operations of the dryer, the cycling thermostat regulates the flow of power to the heating unit. More power is supplied to enable the dryer to reach its proper operating temperature. The TOC is only activated when it senses that the dryer temperature has crossed its operational limit. It should then cut power to the heater. This component prevents the dryer from overheating and in extreme cases will prevent the occurrences of fire breaking out.

A vast majority of dryer problems are seen to originate from the TOC because it has tripped. In many instances, this is seen to occur when the dryer door has been opened before it has had time to cool down sufficiently. This has the effect of raising the temperature within the dryer, which causes the TOC to trip.

The popular use of thermostats that cannot be reset is an issue to consider, and in such cases the thermostat should be replaced before the dryer is considered safe to use. Do not attempt to circumvent the TOC or modify it, as this could prove to be a safety hazard.

The Importance of Airflow

Maintaining the proper ventilation and airflow is necessary to ensure the optimal functioning of your dryer.

The dryer functions by pulling in air from the room. This air is then heated by an electrical or gas heater before it is blown out through the clothes in the dryer to aid the condensation process. 

Without an adequate air supply, the dryer will not be able to pull in air for the drying process, and improper ventilation prevents it from expelling any waste water vapor and hot air.

Poor airflow will affect the drying efficiency of the appliance. As a result the dryer takes an unusually long time to dry out your clothes. This increases the duration for which the heater remains active, and will increase your energy usage and costs.

Problems related to lack of airflow can be easily solved and will improve the performance/energy-efficiency of your appliance. You can inspect the dryer filters to ensure that they are not clogged and blocking the flow of air. These filters can be easily cleaned or replaced, if required.

Always make sure that the dryer is installed at a location where there is adequate ventilation. Do not place it in a confined space and ensure that all vents are clear and free from of obstructions.

Following these steps can help you avoid most tumble dryer problems. There are, however, a few other types of problems that may occur.

The Dryer does not start

A dryer that appears to be dead is most likely affected by a defective door switch or a broken/bent plunger. In most cases, a worn out door switch is a normal by-product of regular use. However, rough handling of the door can increase the likelihood of damage to the switch.

The first step though, is to inspect the plunger that is mounted on the door. If it has fallen off or sustained any physical damage, it should be replaced. In case the plunger is fine you can then move on to inspecting the door switch. This component may be accessed via the top cabinet panel. Using an Ohm meter, you may test the continuity of the switch. If the switch checks out, you can move on to the thermal fuse that is usually located on the blower assembly.

In most gas dryers this may be accessed via the bottom panel, while in an electric dryer, the fuse may be reached through the rear service panel.

In case there is no continuity in the thermal fuse, it should be replaced. However, you must be aware that a blown thermal fuse is an indicator of a more serious problem. Generally, this is indicative of a defective thermostat or blocked vent. These issues should also be dealt with before changing the fuse.

The Dryer is noisy during operation

Dryer noises will typically indicate that the Drum Support Rollers have been worn out and are not functioning efficiently. All the rollers should be replaced in such situations. If this does not solve the problem, you will also need to change the Tensioner Roller. In most cases, it is advisable to replace both rollers simultaneously. 

The Dryer produces no heat

If your gas or electric dryer is unable to generate heat, but continues to tumble, it could indicate a defect in the thermal fuse or cut out, which should be checked for continuity. In case the thermal fuse exhibits continuity, you may need to check the radiant sensor (on a gas dryer).  This component tracks the igniter temperature and is responsible for activating the gas valve coils. If this sensor is defective, it will prevent the activation of the heating system in a gas dryer. When the sensor has no continuity, it should be replaced. In case the sensor appears to be fine, remove the electrical connector to the igniter and check this device with an Ohm meter. A properly functioning sensor and igniter would indicate a problem with the gas valve coils.

The coils may be replaced after extracting the retaining plate. The sensor should also be unplugged and pulled away from the gas valve.

If you are dealing with an electric dryer and the thermal fuse appears to work, you will need to check the continuity of the heater element. Remove all wires that are connected to the heating element before testing it. If this component has malfunctioned, it should be replaced. The heating element may be accessed by removing the clip located at the top of the heater assembly. The box may be pulled out and the defective part can be replaced.

The Dryer does not rotate, but the motor runs

In most cases, this should be a simple matter of replacing a broken belt. Pull away the front cabinet panel and lift the drum away from the holding cabinet. You can use a vacuum cleaner to get rid of lint or any other trapped materials. Check the tensioner roller by rotating it manually. Make sure that is able to move without restriction and that there are no visible cracks or breaks. Place the new belt around the drum and replace it within the cabinet.

Extend your hands around the blower assembly to reach some of the tensioners that are located behind the motor. Lifting up the tensioner will allow you to align the belt correctly around the motor pulley.