Whirlpool Dryer Hi-Limit Thermostat/Inlet Thermistor Testing and Replacement

Scritto Da: Bill Gilbert

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Whirlpool Dryer Hi-Limit Thermostat/Inlet Thermistor Testing and Replacement

Difficoltà

Difficult

Passi

Tempo Necessario

3 - 5 ore

Introduzione

Use this guide to test the hi-limit thermostat/inlet thermistor on your Whirlpool Dryer and replace it if necessary. These components are combined into one unit, so if either component fails, you will need to replace the whole unit.

These components control your dryer's temperature. The inlet thermistor lets the main board know what the inlet temperature is, and the hi-limit thermostat shuts off the heater if it overheats. The hi-limit will reset and allow the heating element to operate again after a cooling period.

When the hi-limit fails, the dryer may not heat at all, or sometimes it will overheat until the thermal cutoff or thermal fuse operates. When the inlet thermistor fails, your machine will display an error code.

This guide is rated as difficult, mainly because of the amount of disassembly required. None of the steps are particularly difficult in themselves, except perhaps removing the front lower bulkhead.

This guide will work for most electric Whirlpool dryers. This guide is written with a model WED87HED dryer. If you have a different model, you may encounter some minor disassembly differences, but the overall repair process will be the same.

Strumenti

Passo 1

Before you begin your repair, unplug your dryer.
Your power cord may have four prongs rather than three. The additional prong is a ground connection.

Passo 2

Throughout this guide, keep track of each screw and reinstall it exactly where it came from.
Use a nut driver to remove the screws securing the top panel to the rear panel bracket.

Passo 3

Grasp the top and slide it 1/2 to 1 inch toward the rear of the machine.

Passo 4

Lift the top panel upward to separate it from the chassis.
Remove the top panel from the machine.

Passo 5

Disconnect the control panel cable from the main board.

Passo 6

Disconnect the drum light connector.

Passo 7

Remove the screws securing the control panel.

Passo 8

Lift the control panel up and tilt it away from the chassis to remove it.
Make sure to thread the cable through the hole in the chassis.
During reassembly, thread the cable through its proper hole before reinstalling the control panel.

Passo 9

Use a small flat blade screwdriver or a spudger to unlatch both sides of the door switch connector.
Unplug the connector.

Passo 10

Remove the upper front panel sheet metal screws.
Tilt the machine backwards and prop it securely, or have a friend hold it.
Remove the sheet metal screws on the bottom edge of the panel.

Passo 11

Remove the screws inside the door area below the drum opening.

Passo 12

The panel is heavy and awkward. You may want to have a friend help you with this step.
Pull the bottom of the panel away from the chassis about two to three inches.
Lift the front panel off the small tabs on the chassis near the top of the panel and remove it.
Make sure you don't snag the door switch wire harness as you remove the panel.

Passo 13

Remove the cover plate screw.

Passo 14

Remove the cover plate.

Passo 15

Remove the screws securing the cord cables.
Mark the cables with a permanent marker if needed and take a picture or draw a diagram.

Passo 16

Pull the cord carefully down through the round hole.
Make sure you replace the connections correctly when you reassemble.

Passo 17

Remove the green ground screw.
Remove the cord terminal block screws.

Passo 18

Move the cord terminal block behind the rear panel.

Passo 19

Remove the rear panel screws.
Throughout this guide, keep track of each screw and reinstall it exactly where it came from.

Passo 20

Remove the screw holding the main board bracket to the chassis.
Remove the screws from the top rear of the machine.

Passo 21

Put on gloves before continuing, as the rear panel is sharp.
Lift the panel about 1/2 inch and tilt it to the rear to release it from the vent pipe.
Slide the panel off the vent pipe and remove it.

Passo 22

During reassembly, perform the following:
Make sure that the vent pipe is fitted into the collar on the panel.
Make sure the tabs at the bottom are aligned to the bottom rim of the chassis.
Position the panel so its screw holes match with the chassis.

Passo 23

Pull the lint filter up out of the lint filter slot to remove it.
These photos show the front panel in place, but the procedure is the same if the front panel is already removed.

Passo 24

Remove the mounting screws securing the lint filter housing.

Passo 25

Pull the filter housing outward from the chassis and down to remove it.

Passo 26

Squeeze the locking tabs on the moisture sensor connector.
Disconnect the connector.

Passo 27

Label, photograph or make a sketch of the connector locations and of the main board bracket position on your machine.
Disconnect all of the connectors on the main board front half.

Passo 28

Label, photograph or make a sketch of the connector locations and of the main board bracket position on your machine.
Disconnect all the connectors from the rear half of the main board.

Passo 29

Remove the sheet metal screw that retains the main board to the main board bracket.

Passo 30

Lift the rear corner of the main board nearest to the side walls of the chassis.
You want to release the locking tab on the side of the main board.
Slide the main board toward the front of the dryer to release the tabs securing it to the main board bracket.

Passo 31

Remove the main board from the main board bracket.

Passo 32

Remove the sheet metal screw holding the main board bracket.

Passo 33

Lift off the main board bracket from the chassis and turn it so the bottom is exposed.
Using long nose or slip joint pliers, pinch the locking wings of the harness retainer clamp.
Separate the harness from the main board bracket and remove the main board bracket.

Passo 34

Remove the screws securing the upper front bulkhead to the front of the chassis.
Remove the sheet metal screws securing the top plastic portion to the upper front bulkhead.

Passo 35

Remove the upper front bulkhead and set it aside.

Passo 36

Take careful note of the belt path before proceeding.
Be careful during this procedure! The idler arm is under spring tension and may pinch you, or it could damage the belt switch if the arm is allowed to snap down.
Push the idler arm (the metal upside-down "L") up to relieve the tension on the drive belt.
Remove the belt from the motor pulley.
Gently lower the idler arm until it rests parallel to the dryer floor.
During reassembly, refer to your notes or the belt path link to rethread the drive belt.

Passo 37

Remove the screws securing the lower front bulkhead.

Passo 38

While supporting the drum, lift the lower front bulkhead off of the hooks on the chassis.

Passo 39

Lower the bulkhead about 2 inches to free the drum rollers tucked under the drum.
While supporting the drum, remove the lower front bulkhead.
During reassembly, tilt the bulkhead to the right to get the rollers under the lip on the front of the drum. Once the drum is on the rollers, you can move the bulkhead to the upright position.

Passo 40

Use the belt to lift the drum a few inches.
Swing the drum out of the front of the dryer.
Note which end of the drum faces the front.
If the belt is broken, stand in front of the drum and put your arms inside it. Lift it up and pull it through the front opening of the machine. Having someone to help you with this is a good idea.
Make sure you get your drum back on the rollers when you reinstall the lower front bulkhead. Take your time and don't force it.

Passo 41

The following steps show how to test and replace the hi-limit thermostat/inlet thermistor.

Passo 42

Pull the spade connectors straight off to disconnect the hi-limit thermostat portion of the hi-limit thermostat/inlet thermistor.
Be sure to grip the connectors and not the wire when disconnecting.

Passo 43

If you do not need to test the hi-limit thermostat, skip this step.
This step requires a multimeter. If you aren't familiar with how to use one, here is a guide that will help you.
With the hi-limit thermostat disconnected, you can check it for continuity. It should show continuity (less than 1 Ω) at room temperature.
If it shows OL or anything above 1 Ω, replace it.

Passo 44

If your hi-limit thermostat does not have this thermistor, skip this step.
Free the inlet thermistor connector by lifting the black locking tab with a small flathead screwdriver or spudger.
The locking tab is fragile, so only lift it a small amount to free the connector. Make sure to grasp the connector, not the wires when disconnecting them.
Once freed, pull the connector straight out to disconnect the inlet thermistor.

Passo 45

Remove the sheet metal screws securing the hi-limit thermostat/ inlet thermistor.

Passo 46

Remove the unit by pulling it straight out from the mounting hole.
If your hi-limit thermostat does not have a thermistor attached, you may skip the next step.
Note the orientation for reassembly.

Passo 47

This step shows how to test the inlet thermistor. If you just need to replace the hi-limit thermostat or inlet thermistor, you can skip this step.
With the thermistor removed from the heater housing, test for resistance with the multimeter across the two small terminals.
The resistance values of this component vary. You may be able to locate a tech sheet booklet in the chassis of the dryer to find the value.
If the device shows outside the correct range, replace it.

Conclusione

To reassemble your device, follow these instructions in reverse order.

Repair didn’t go as planned? Ask our Answers community for help.

Autore

Bill Gilbert

Membro da: 30/06/22

29837 Reputazione

Whirlpool Dryer Hi-Limit Thermostat/Inlet Thermistor Testing and Replacement

Introduzione

Strumenti

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