Dryer Thermostat WP8557403 – What Part Fixes This Problem?
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Understanding the Problem
What WP8557403 is and why it matters: WP8557403 is a dryer temperature/limit thermostat used on many Whirlpool/Maytag/Kenmore dryers. It senses temperature in the heater/air path and either cycles the heater on and off (cycling thermostat) or acts as a safety cutoff (high-limit thermostat). When it fails open or intermittently, the dryer can stop heating, overheat, or run erratically. Step-by-step diagnostic and repair instructions: 1. Safety first: Unplug the dryer or turn off the circuit breaker before you start. Confirm power is off. 2. Gather tools: multimeter (continuity/ohms), screwdrivers, nut drivers (1/4" and 5/16" typically), needle-nose pliers, flashlight, and the replacement part (WP8557403). 3. Access the thermostat: Depending on your model the thermostat is usually behind the rear panel, the front panel near the lint screen, or mounted on the heater box/blower housing. Remove the access panel(s) to reach the thermostat. 4. Visual inspection: Look for burned terminals, melted housing, or disconnected wires. Also inspect the heater element and vent for signs of overheating (heavy soot, melted plastic). 5. Identify and label wires: Before disconnecting, label or photograph the wire locations so reassembly is simple. There are typically 2–3 spade terminals. 6. Test continuity at room temperature: Set the multimeter to continuity or lowest ohms range. With the thermostat disconnected from wires, place probes on the terminal(s). A properly functioning normally-closed thermostat should show continuity (near 0 ohms) at room temperature. If it shows OL (open) at room temp, the thermostat is failed and needs replacement. 7. Additional checks: If thermostat shows continuity but the dryer still won’t heat, test the thermal fuse and heating element for continuity, and inspect the vent for blockage. A clogged vent can cause repeated thermostat/limit failures. 8. Replace the thermostat: Remove mounting screw(s) and pull the thermostat free. Install the new WP8557403 in the same orientation, secure the mounting screw, and reconnect wires to the same terminals. 9. Reassemble and test: Reinstall panels, restore power, and run a test cycle. Check for normal heat operation and that the dryer does not overheat. Monitor the first run to ensure proper cycling and no abnormal smells or smoke. 10. Final check: After a successful test, clean the lint trap and verify the exhaust vent is clear to prevent future overheating and thermostat stress. Safety note: Never bypass a thermostat or safety limit. Replacing thermostats and working near heating elements can expose you to sharp edges and electrical shock. Always confirm power is off and follow manufacturer instructions.
Common Symptoms
Dryer not heating, dryer overheats and trips thermal fuse, dryer runs but cycles off too quickly, or intermittent heating.
Common Causes
- Internal thermostat contacts failed/open (age or heat stress)
- Restricted venting causing overheating and damaging the thermostat
- Faulty heating element or thermal fuse causing secondary thermostat stress
Popular Parts That Fix This Problem
These are the most common replacement parts that fix this problem. When you're ready to order, click below to find the right part at ProsourceParts.com — just search by your appliance model number for a guaranteed fit.
Helpful Repair Tip
Confirm failure with a multimeter: a normally-closed thermostat should show near-zero ohms at room temperature. If open (no continuity) at room temp, replace it.
Frequently Asked Questions
How do I know if WP8557403 is the part that needs replacing?
Unplug the dryer, access the thermostat, disconnect the wires, and test with a multimeter. If the thermostat is 'open' (no continuity) at room temperature when it should be closed, it’s bad and should be replaced. Also look for visible heat damage or melted terminals.
Can I keep using the dryer if the thermostat is faulty?
No. A failed thermostat can cause no heat (dryer won't dry) or allow overheating (risking a fire or repeated thermal fuse failure). Replace the thermostat before regular use. If you’re uncertain about the repair, contact a qualified appliance technician.
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