How to Troubleshoot Power Supply in a Dryer

DryerModerate⏱ 30 minutes - 1 hour

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Use this guide to check whether an electric dryer that will not run or will not heat is getting the power it needs. An electric dryer needs about 240 volts AC for the heater and about 120 volts AC for the motor and controls. These checks help you decide whether the problem is in the home power supply, the dryer cord, or inside the dryer. This guide covers common three-prong and four-prong dryer outlets, though exact wiring layouts may vary slightly.

🧰 Tools

Flathead Screwdriver
Phillips #2 Screwdriver
Digital Multimeter

ШагиSteps

Prepare for electrical testing

Gather a multimeter, a flathead screwdriver, and a Phillips screwdriver.
Use a multimeter with intact probes and a voltage rating suitable for household power.
Electric dryers use 240 volts AC, which can seriously injure or kill you.
Keep your fingers on the insulated parts of the probes and away from metal terminals, prongs, and slots.
Work on a dry floor with dry hands, and stop if you are not comfortable testing live voltage.

Expose the terminal block

Move the dryer far enough to reach the back panel where the power cord enters the cabinet.
Remove the cover plate over the power-cord connection with a screwdriver.
Identify the three terminal-block screws where the cord wires connect to the dryer.
The two outside screws are the hot terminals, and the center screw is neutral.

Test voltage at the terminal block

Plug the dryer in and set the multimeter to AC volts.
Touch one probe to the left screw and the other to the center screw; the meter should read about 120 volts AC.
Touch one probe to the center screw and the other to the right screw; the meter should read about 120 volts AC.
Touch one probe to each outside screw; the meter should read about 240 volts AC.
Do not let the probe tips slip or touch two terminals at the same time.
If all three readings are correct, the dryer is getting proper incoming power and the fault is inside the dryer.
If a 120-volt or 240-volt reading is missing, unplug the dryer and continue testing toward the outlet and breaker.

Check the power cord for continuity

Unplug the dryer before testing the power cord for continuity.
Set the multimeter to continuity or resistance mode.
Touch one probe to a terminal-block screw and the other to the matching prong on the dryer plug.
Repeat this check for the other outside terminal and for the center terminal to its matching neutral or ground prong.
A beep or low resistance means that wire in the cord has continuity.
An open or no-continuity reading means that prong does not connect to its wire, so the dryer cord should be replaced.
If the cord tests good but the dryer still is not getting proper voltage, continue with the wall outlet.

Set up the outlet test

Leave the dryer unplugged and set the multimeter to AC volts.
Look at the dryer outlet and identify whether it has three prongs or four prongs.
A three-prong outlet has two flat hot slots and one neutral slot.
A four-prong outlet has two outside hot slots plus separate neutral and ground slots.
Insert the probes far enough to touch the metal contacts inside the outlet slots.
Keep your fingers away from the metal probe tips and outlet openings during these checks.

Test a three prong outlet

Place one probe in the neutral slot and the other in one flat hot slot; the meter should read about 120 volts AC.
Move the probe from the first hot slot to the other flat hot slot while keeping the other probe in neutral.
The meter should read about 120 volts AC on the second hot-to-neutral test as well.
Place one probe in each flat hot slot; the meter should read about 240 volts AC.
If all three readings are correct, the outlet is supplying proper voltage.
If any reading is missing, the outlet may have a loose, burned, or disconnected wire, or the breaker may be faulty.

Test a four prong outlet

Identify the two outside flat slots on the four-prong outlet; these are the hot slots that provide 240 volts between them.
Test one outside hot slot to the neutral slot; the meter should read about 120 volts AC.
Test the same hot slot to the ground slot; the meter should also read about 120 volts AC.
Repeat both 120-volt tests from the other outside hot slot to neutral and ground.
Place one probe in each outside hot slot; the meter should read about 240 volts AC.
If any required reading is missing, inspect the outlet wiring and breaker next.

Inspect the dryer outlet wiring

Find the circuit breaker that controls the dryer outlet and switch it off.
Confirm that the outlet is dead before removing it from the box.
Remove the outlet cover and pull the outlet from the electrical box with a screwdriver.
Inspect the wires on the back of the outlet for burned ends, loose connections, or disconnected wires.
Repair damaged outlet wiring before using the dryer again.
Have a qualified electrician repair outlet wiring if you are not trained to do it safely.

Inspect the circuit breaker

Go to the breaker panel and identify the double-pole breaker that controls the dryer.
Switch the breaker fully off, then back on, to reset a tripped breaker.
Do not remove the panel cover or touch internal panel parts unless you are qualified to work inside a live electrical panel.
With the breaker off, a voltage test from either breaker screw to metal ground or neutral should show no voltage.
With the breaker on, each breaker screw to metal ground or neutral should read about 120 volts AC.
With the breaker on, testing across the two breaker screws should read about 240 volts AC.

Interpret the breaker results

Replace the breaker if it does not provide about 240 volts AC across the two breaker screws while switched on.
If the breaker output is correct but the outlet readings are wrong, the problem is between the breaker and the outlet.
If the outlet and cord test good but the terminal-block readings are wrong, inspect the cord connections at the dryer.
If the terminal block shows about 120 volts from each hot to neutral and about 240 volts hot to hot, continue troubleshooting inside the dryer.
A dryer that runs, shuts off, and later runs again may have an overheating breaker, but a failing motor is also a common cause.

Reinstall any outlet covers, terminal block covers, and access plates before using the dryer. Repair didn't go as planned? Ask our Answers community for help.

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