Introduction
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.
What you need
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Use a nut driver to remove the screws securing the top panel to the rear panel bracket.
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Grasp the top and slide it 1/2 to 1 inch toward the rear of the machine.
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Lift the control panel up and tilt it away from the chassis to remove it.
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Use a small flat blade screwdriver or a spudger to unlatch both sides of the door switch connector.
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Unplug the connector.
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Remove the upper front panel sheet metal screws.
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Tilt the machine backwards and prop it securely, or have a friend hold it.
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Remove the sheet metal screws on the bottom edge of the panel.
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Pull the bottom of the panel away from the chassis about two to three inches.
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Lift the front panel off the small tabs on the chassis near the top of the panel and remove it.
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Remove the green ground screw.
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Remove the cord terminal block screws.
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Remove the rear panel screws.
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Lift the panel about 1/2 inch and tilt it to the rear to release it from the vent pipe.
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Slide the panel off the vent pipe and remove it.
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Make sure that the vent pipe is fitted into the collar on the panel.
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Make sure the tabs at the bottom are aligned to the bottom rim of the chassis.
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Position the panel so its screw holes match with the chassis.
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Pull the lint filter up out of the lint filter slot to remove it.
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Remove the mounting screws securing the lint filter housing.
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Pull the filter housing outward from the chassis and down to remove it.
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Squeeze the locking tabs on the moisture sensor connector.
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Disconnect the connector.
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Disconnect all of the connectors on the main board front half.
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Remove the sheet metal screw that retains the main board to the main board bracket.
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Lift the rear corner of the main board nearest to the side walls of the chassis.
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Slide the main board toward the front of the dryer to release the tabs securing it to the main board bracket.
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Remove the sheet metal screw holding the main board bracket.
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Lift off the main board bracket from the chassis and turn it so the bottom is exposed.
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Using long nose or slip joint pliers, pinch the locking wings of the harness retainer clamp.
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Separate the harness from the main board bracket and remove the main board bracket.
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Remove the screws securing the upper front bulkhead to the front of the chassis.
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Remove the sheet metal screws securing the top plastic portion to the upper front bulkhead.
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Push the idler arm (the metal upside-down "L") up to relieve the tension on the drive belt.
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Remove the belt from the motor pulley.
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Gently lower the idler arm until it rests parallel to the dryer floor.
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While supporting the drum, lift the lower front bulkhead off of the hooks on the chassis.
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Use the belt to lift the drum a few inches.
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Swing the drum out of the front of the dryer.
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The following steps show how to test and replace the hi-limit thermostat/inlet thermistor.
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Pull the spade connectors straight off to disconnect the hi-limit thermostat portion of the hi-limit thermostat/inlet thermistor.
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With the hi-limit thermostat disconnected, you can check it for continuity. It should show continuity (less than 1 Ω) at room temperature.
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If it shows OL or anything above 1 Ω, replace it.
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Free the inlet thermistor connector by lifting the black locking tab with a small flathead screwdriver or spudger.
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Once freed, pull the connector straight out to disconnect the inlet thermistor.
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Remove the sheet metal screws securing the hi-limit thermostat/ inlet thermistor.
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Remove the unit by pulling it straight out from the mounting hole.
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With the thermistor removed from the heater housing, test for resistance with the multimeter across the two small terminals.
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If the device shows outside the correct range, replace it.
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To reassemble your device, follow these instructions in reverse order.
Repair didn’t go as planned? Ask our Answers community for help.
To reassemble your device, follow these instructions in reverse order.
Repair didn’t go as planned? Ask our Answers community for help.
