Short answer: To test a dryer motor, use a multimeter to check for continuity in the motor windings and ensure the motor starts when power is applied.
When your dryer refuses to heat up or turn, troubleshooting the problem becomes essential to restore its functionality. Among the various components that can go awry, the dryer motor is a critical element to examine. Knowing how to test a dryer motor is a valuable skill that can help you pinpoint the source of the issue and potentially save on repair costs. In this guide, we’ll explore the systematic steps to determine if the dryer motor is indeed the culprit when your appliance isn’t performing as expected, providing you with the confidence to diagnose and address motor-related problems effectively.
- Identify the Problem: When a dryer doesn’t start but makes a humming sound, it could be due to various issues, such as a faulty motor, a blocked blower wheel, or electrical problems. Testing the motor helps pinpoint the root cause, making it easier to address the problem effectively.
- Cost-Efficiency: Replacing a dryer motor can be an expensive repair. By testing the motor first, you can avoid unnecessary expenses by ensuring that the motor is indeed the issue. This prevents you from replacing a motor that may be in working condition.
- Safety: Electrical appliances like dryers can pose safety risks if not functioning correctly. A defective motor may lead to overheating or other electrical problems, potentially causing a fire hazard. Testing the motor ensures the appliance is safe to use.
- Extended Appliance Life: Repairing or replacing a faulty motor can extend the life of your dryer. Neglecting motor issues may lead to further damage, affecting other components and potentially rendering the dryer irreparable.
- Energy Efficiency: A malfunctioning motor may result in the dryer consuming more energy to perform its job inefficiently. Testing and repairing the motor can help improve energy efficiency, saving you money on utility bills in the long run.
- Environmental Impact: Repairing appliances instead of replacing them is more environmentally friendly. By diagnosing and fixing the motor, you contribute to reducing electronic waste and conserving resources.
How To Test A Dryer Motor?
If a dryer won’t start when you press the start button but you hear a humming sound, there’s a strong probability that the dryer’s drive motor has failed. To help determine this, inspect the dryer’s blower wheel for obstructions that may prevent it from turning freely by hand. If the wheel doesn’t rotate freely, it’s likely that the bearings in the drive motor have seized, and the motor will need replacement.
To further test the drive motor using a multimeter, follow these steps:
- Document the location of the wires connected to the motor.
- Disconnect those wires or the motor’s wire harness connector.
- Refer to the appliance’s wiring diagram to determine the location of the motor’s start and run windings.
- Isolate the start and run windings, if possible, by detaching the wires.
- Rotate the multimeter’s range selection dial to the lowest setting for ohms of resistance.
- Contact the black meter lead to the motor protector terminal and the red lead to the start winding wire terminal.
- If the meter displays two to five ohms of resistance, the drive motor’s start winding has electrical continuity.
- Keeping the black meter lead on the motor protector terminal, move the red meter lead to the run winding wire terminal.
- Check for proper electrical continuity in the run winding as well. Both windings should show two to five ohms of resistance.
- If the meter doesn’t change when testing either the start or run winding, the motor has no continuity and is defective.
Using Multimeter
You can also use the multimeter to test the motor’s thermal protector to confirm that the motor can receive the voltage it needs to run:
- Disconnect the wires from the thermal protector terminals.
- Contact the black meter lead to one of the thermal protector terminals and the red lead to the other terminal.
- If the thermal protector has proper continuity, the multimeter display will indicate close to zero ohms of resistance.
- If the thermal protector has no continuity, the entire motor will need replacement with a new one.
Testing The Motor Switch On A Dryer
Step 1: Check the Motor Switch:
- Inside the dryer motor, there’s a centrifugal switch.
- When the motor starts spinning, a black disc inside the motor moves.
- On the bottom of the switch, there’s a small arm that also moves.
- This arm controls a contact for the heater. It breaks the circuit to the heater when the motor isn’t running.
Step 2: Inspect the Switch:
- Sometimes, these switches can go bad, or the small arm above the black disc may break off.
- To check, unplug the dryer and remove the cover.
Step 3: Cleaning and Testing:
- Examine the switch for any visible issues.
- If it’s just dirty or has carbon buildup, you can use sandpaper or contact cleaner to clean it.
- Ensure that the switch functions properly by making and breaking contact when the motor starts and stops.
Step 4: Avoid Bypassing:
- I strongly advise against bypassing this switch because it’s a safety feature.
- Bypassing it would cause the heater to stay on even when the motor isn’t running, creating a fire hazard.
Step 5: Final Check:
- Locate the switch with a couple of big red wires connected to it (where my alligator clips are).
- Make sure the heater heats up when the switch functions correctly.
- If the switch is faulty, it could be the reason your dryer isn’t heating.
How Do I Know If The Dryer Motor Is Bad?
Determining if your dryer motor is bad involves a few diagnostic steps. Here’s how to know if your dryer motor is likely the problem:
- Check for Electrical Power: Ensure that the dryer is properly plugged in and receiving electrical power. Sometimes, a blown fuse or tripped circuit breaker can give the appearance of a motor issue.
- Start Button and Humming Sound: When you press the dryer’s start button, listen for a humming sound. If you hear a hum but the dryer drum doesn’t spin, it suggests the motor may be getting power but not turning the drum.
- Drum Rotation: Try to manually rotate the dryer drum. If it moves freely, it’s less likely that the motor is the problem. If the drum is difficult to turn or doesn’t move at all, the motor may be seized.
- Inspect for Burnt Smell: If the motor has burned out, you may detect a burnt odor when attempting to start the dryer.
- Visual Inspection: Remove the dryer’s access panel and visually inspect the motor. Look for any obvious signs of damage, such as burnt wires, loose connections, or a broken belt that connects the motor to the drum.
- Check for Motor Continuity: Using a multimeter set to measure resistance (ohms), you can test the motor’s windings for continuity. Disconnect the motor from the power source and follow these steps: a. Locate the wires connected to the motor and document their positions. b. Disconnect the wires. c. Refer to the appliance’s wiring diagram to identify the start and run windings. d. Measure the resistance between the motor protector terminal and the start winding wire terminal. It should show 2 to 5 ohms of resistance. e. Then, measure the resistance between the motor protector terminal and the run winding wire terminal. Again, it should show 2 to 5 ohms of resistance. f. If either winding does not show continuity (i.e., no resistance reading), the motor is likely bad and needs replacement.
- Centrifugal Switch Check: Inspect the centrifugal switch inside the motor. Ensure that it moves freely and makes and breaks contact as the motor starts and stops. A malfunctioning centrifugal switch can cause the motor to fail.
- Consult a Professional: If you’re not comfortable performing these tests or if the issue remains unclear, it’s advisable to consult a professional appliance technician. They can provide a more accurate diagnosis and repair or replace the motor as needed.
FAQs
What is the voltage of a dryer motor?
The voltage of a dryer motor typically depends on the region and electrical system. In the United States, most dryer motors operate on 120 volts for residential dryers. However, some larger or commercial dryers may use 240 volts. It’s essential to check the specifications of your specific dryer model to determine the voltage it requires.
Are dryer motors AC or DC?
Dryer motors are typically AC (Alternating Current) motors. They run on the AC power supplied by your home’s electrical system. AC motors are commonly used in appliances like dryers due to their reliability and efficiency.
How much power does a dryer motor have?
The power rating of a dryer motor can vary depending on the dryer’s size and design. Residential dryer motors generally have power ratings in the range of 1/4 to 1/3 horsepower (HP), which is approximately 187 to 250 watts. Larger commercial dryers may have more powerful motors.
Does a dryer need a drain?
No, a typical clothes dryer does not need a drain. Dryers work by evaporating moisture from wet clothes and venting it outside through a duct or vent system. There is no need for a drain connection, as the water vapor is expelled as hot air through the vent.
Conclusion
Testing a dryer motor is a systematic process that involves several key steps. By carefully checking for power supply, listening for motor sounds, inspecting the drum’s movement, and conducting electrical continuity tests, you can effectively diagnose whether the dryer motor is functioning correctly or if it’s the source of the problem when your dryer isn’t heating or spinning. Identifying motor issues early can save on unnecessary repair costs and ensure the safe and efficient operation of your appliance, making it a valuable skill for any dryer owner or technician.
