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Duet Whirlpool Dryer Not Heating? Here’s Why (+ How To Fix)

The Whirlpool Duet series has gas and electric dryers, so the reason for your model not heating depends on the type. Also, if your Whirlpool dryer doesn’t heat up to a set temperature, that isn’t the same issue as the unit not heating at all. So, why’s your Duet Whirlpool dryer not heating?  

Here’s why your Duet Whirlpool dryer is not heating:

  • The thermal fuse is blown.
  • The thermistor is cycling off.
  • The heating element is bad.
  • The gas valve coils are failing.
  • The gas igniter isn’t working.
  • The flame sensor is broken.
  • The moisture sensor is bad.
  • The relay isn’t functioning.
  • Causal or facilitating issues.

In most cases, the problem is the heating system and related components. However, a few issues that aren’t directly related to the heating element or gas burner assembly can also be the cause or a facilitating factor. Read on to know why your Duet Whirlpool dryer is not heating. 

The Thermal Fuse Is Blown

The thermal fuse is a safety fixture in both gas and electric dryers in the Whirlpool Duet series. Electric dryers have two thermal fuses, whereas the gas Duet models have only one. Regardless of the number, your Duet Whirlpool dryer won’t heat if you have a blown thermal fuse.

The thermal fuse is among the likeliest culprits if you suddenly find your dryer not heating one day. Fortunately, this tiny yet critical part is an inexpensive problem to fix. Also, it is easy to test whether the thermal fuse is broken or not. 

I must mention here that a blown thermal fuse is a consequence. This outcome could be due to a failed part (as in the fuse itself) or other factors causing your dryer to overheat and blow its fuse. So, you must also address those issues to prevent a new thermal fuse from blowing.

How To Fix

Test the thermal fuse and replace it if it has no continuity. Here are the steps:

  1. Unplug the Whirlpool Duet dryer (gas or electric).
  2. Remove the kick plate or front panel (subject to the model).
  3. Get a 1/4 inch socket or nut driver to take out the screws.
  4. Locate the blower and heating assemblies at the bottom.
  5. Find the thermal fuse(s) ー Duet gas dryers only have one thermal fuse on the blower assembly, while electric dryers have a second one on the heating element assembly.
  6. Take a picture of the wiring so you can reassemble it accordingly once you’re done.
  7. Remove the wire harnesses of one or both fuses (subject to the model).
  8. Test the thermal fuse terminals for continuity with a multimeter.
  9. You may also set the multimeter to least resistance to test the same.
  10. Replace the fuse if it has no continuity and nil or infinite resistance.
  11. If one or both fuses have continuity, test the adjacent thermistor.

You’ll find the part number on the thermal fuse; match it when you buy a replacement. While the thermal fuse on Duet Whirlpool dryers isn’t unique, you must try to get a manufacturer-approved replacement. 

The Thermistor Is Cycling Off

Whirlpool Duet dryers have a thermistor regulating the heating cycle. This sensor isn’t exactly a thermal fuse; it’s more of a thermostat. If you have a gas Duet Whirlpool dryer, there’s only one thermistor on the blower assembly. An electric variant has another next to the heating element.

A bad thermistor prevents a Duet Whirlpool dryer from heating or reaching a high temperature. Unlike a fuse that won’t let the heating element or burner start, a failing thermistor will shut the dryer prematurely by erroneously detecting a massive temperature spike (i.e., overheating).

Some readers may not be familiar with thermal fuses and thermistors, especially when they are next to one another on Duet dryers. 

When you disassemble your unit to access the components, the slender thermal fuse is usually towards your left on the blower assembly. The rounder thermistor or cycling thermostat is to the right. This alignment is standard in Whirlpool Duet gas and electric dryers. 

For electric Duet models, the second thermistor is on the heating assembly after the element’s wiring. So after removing the kick plate or front panel, you’ll sequentially find the heating element wires, the second thermistor, and the second thermal fuse farthest from you.

How To Fix

You can test the thermistor after removing the wires. Alternatively, you can unscrew and take it out of the assembly to test for resistance. Whatever you do, take a picture of the wiring harness to avoid guesswork when reinstalling the thermistor.

You cannot test thermistors, recycling thermostats, and high limit switches for continuity, as they regulate the circuit only for a rated temperature range. Otherwise, the switch remains off, and the circuit is open. So set the multimeter to ohms and test the thermistor’s resistance.  

A dryer thermistor or cycling thermostat should read around 2,000 or 3,600 to 7,200 ohms. If the reading shows no or infinite resistance or an open loop. 

You can perform this test for both thermistors on electric Duet models, but only one is likely to be broken. However, your dryer may have a bad thermistor along with a broken thermal fuse, so check all these sensors and replace the bad ones after matching the part number.  

The Heating Element Is Bad

If your Duet electric dryer’s thermal fuses and thermistors are alright, check the heating element. A Whirlpool Duet dryer won’t heat if the element doesn’t work or the coil is too weak. Also, inspect the wires and connections and test the element to see whether it’s shorted. 

How To Fix

Here are the recommended solutions to fix a bad heating element in a Duet Whirlpool dryer:

  1. Check the wires to ensure the connections are snugly fitted.
  2. Replace frayed, damaged, or burnt wires and connectors.
  3. Test the heating element’s terminals for continuity or resistance.
  4. If there’s no continuity or resistance, you need a new element.
  5. Also, test one terminal of the heating element and the dryer cabinet.
  6. If your multimeter detects continuity, the element or coil has a short.

Depending on your findings, you may replace only the heating element or the entire assembly. An assembly includes the heating element, thermal fuse, and thermistor. 

The Gas Valve Coils Are Failing

Suppose you find your Whirlpool Duet gas dryer’s thermal fuse and thermistor are alright after the continuity and resistance tests, respectively. In that case, check whether the burner comes on and the igniter glows. Also, inspect the burner to see if it fires but shuts down abruptly.

If the igniter glows and the burner still doesn’t fire, there’s no gas in the line, either owing to a lack of supply or failing valve coils, i.e., the solenoids. Verify there’s no issue with the gas supply line or the shut-off valve. Then, you can turn your suspicions to the gas valve coils, igniter, or flame sensor.

How To Fix

Whirlpool Duet gas dryers have two valve coils or solenoids. After removing the kick plate or front panel, you’ll find these atop the burner assembly at the bottom-right inside the dryer. The two coils have 3 and 2 terminals, respectively. Test these terminals for continuity. 

Here are the steps to test and fix bad solenoids or gas valve coils:

  1. Unplug the Duet gas dryer and remove the kick plate or front panel.
  2. Locate the two gas valve coils mounted on the burner assembly.
  3. Take a picture of the wires and unscrew the securing plate.
  4. Pull out the two coils and test their terminals with a multimeter.
  5. If you don’t find continuity on either coil’s terminals, replace it.
  6. You may have to replace both coils if they’re available as a set.
  7. If you find continuity, proceed to test the igniter and flame sensor.
  8. Check the alignment of the gas valve coils while reassembling them.

The Gas Igniter Isn’t Working

A sooty, weak, or broken gas igniter won’t work. As a result, your Duet gas dryer won’t heat. An igniter can wear out in due course, so it won’t glow as brightly or generate sufficient heat to light the flame. Also, a bad igniter won’t trigger the solenoids to turn on the gas supply to the burner. 

How To Fix

Here’s how you can fix or replace a Whirlpool Duet gas dryer’s igniter:

  1. Check if the wirings are alright.
  2. Inspect the gas igniter and clean it.
  3. Replace it if it is broken or cracked. 
  4. Else, test its continuity and resistance.
  5. Replace the igniter if it fails the tests.

The Flame Sensor Is Broken

A Whirlpool Duet gas dryer’s flame sensor can shut off the valve coils or solenoids if it doesn’t detect heat. Even if the igniter works and the burner has fire, a bad flame sensor won’t detect it. That’s why you must inspect the flame sensor if the burner goes off for no other reason.

How To Fix

Test the flame sensor for continuity and check whether the part has a short. In either case, you need a new flame sensor. To test for a short, use the multimeter probes for one terminal of the flame sensor and a part of your Whirlpool Duet dryer’s metal cabinet or body. 

The Moisture Sensor Is Bad

Whirlpool Duet dryers have a moisture sensor in the lint trap. If this sensor fails, the dryer may not turn on its heating element or burner. A failing moisture sensor can also abruptly shut the heating element or burner because the dryer perceives the load to be dry and done. 

How To Fix

Here’s how you can test and fix a bad moisture sensor:

  1. Open the Duet dryer’s door and take out the lint screen.
  2. Locate the moisture sensor (two metal bars) in the lint trap.
  3. Keep the dryer powered and connect the two conductors.
  4. You may use a damp cloth over the two bars for contact.
  5. The dryer should beep and show a code on display.
  6. If there’s no beep, you must replace the moisture sensor.  

The Relay Isn’t Functioning

Whirlpool Duet dryers have a control board under the top console. These control boards have relays that regulate the power supply to the heating element. For gas dryers, the relays regulate the igniter, valves, etc. If these relays don’t work, your Duet Whirlpool dryer won’t heat.

How To Fix

The only way to know whether the relay is working is to inspect the control board to check for signs of burnt components or broken parts. There’s no continuity or resistance test you can perform to know if the control board is in impeccable condition. 

Here’s what you can do with a faulty control board in a Whirlpool Duet dryer:

  1. Unplug the dryer and pull it slightly away from the wall to access the back.
  2. Remove the 5/16-inch (8 mm) screws behind the top cover or panel.
  3. Slide the top cover out and get a 1/4-inch (6.35 mm) socket or nut driver.
  4. Remove the 1/4-inch mounting screws from the control panel housing.
  5. Disconnect the wire harnesses and take out the control board.
  6. Look for signs of damage and repair or replace the control board.
  7. You or a local technician can replace the relays on the board.
  8. Otherwise, you must get a new control board for the Duet dryer. 

Causal or Facilitating Issues

Overheating and obstructed airflow are the main reasons for thermal fuses blowing or dryer thermistors shutting the heating system. So, you must take cognizance of the following causal or facilitating issues:

  • Clogged lint screen
  • Lint trap blockage
  • Blocked exhaust
  • Dirty inlet vents
  • Failing blower
  • Improper duct
  • Power surges
  • Bad wiring, etc.

Whirlpool Duet dryers display a PF error code if there is a power failure when the heating system starts. Likewise, poor or fluctuating voltage at the wall outlet or a circuit breaker issue can prevent the dryer from heating. A power surge can also take out the fuses.

A clogged or failing blower motor disrupts the airflow. The inlet vents behind a Duet dryer can be dirty and blocked, affecting the unit’s airflow. Similarly, long, winding, and poor ductwork for the exhaust vent can impair or obstruct the hot air flowing out of the dryer.

On another note, some of the older Duet dryers have a dial on the control panel. The gear and contacts inside the dial or control timer can break, burn, and deform, which may prevent the heating system from starting. Thus, you must repair or replace the dial, timer, or control switch.     

How To Fix

The specific solution depends on your investigation and diagnosis. Ideally, you should clean the lint screen after every significant load. Likewise, the lint trap and blower should be clean, and the inlet vents and exhaust duct must not have any blockage. Otherwise, the dryer will overheat.