WP3387134 Cycling Thermostat – What Part Fixes a Dryer That Won't Heat or Overheats?
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Understanding the Problem
What it is and what it fixes: The WP3387134 is a cycling (temperature) thermostat used on many Whirlpool/Maytag/KitchenAid/Amana dryers. It cycles the heater on and off to maintain the correct drum temperature. When it fails open, the dryer won’t heat. When it fails closed, the dryer can overheat or run continuously hot. It can also fail intermittently causing inconsistent drying times. Step-by-step diagnostic and repair instructions: 1) Confirm the symptom - Symptom: no heat, weak/intermittent heat, or dryer runs excessively hot. Note whether it’s an electric (240V) or gas dryer — safety steps differ. 2) Preliminary checks (fast, saves time) - Clean the lint filter and vent system. Restricted airflow can cause overheating and damage thermostats. - Verify power: electric dryers need 240V at the terminal block; gas dryers need intact ignition/valve circuits. - Check the thermal fuse (commonly located on the blower housing or exhaust duct). A blown thermal fuse usually causes no heat. 3) Locate the cycling thermostat - On most models the cycling thermostat mounts to the blower housing or bulkhead near the heater assembly. Remove the dryer’s rear panel (or front panel on some models) to access it. 4) Test the thermostat with a multimeter - Unplug the dryer (and shut off gas for a gas dryer) before doing any tests. - Remove the wires from the thermostat terminals (note or photograph wire locations). - Set your multimeter to continuity or lowest ohms scale. - At room temperature the thermostat should normally show continuity (closed). If it reads open (OL/infinite) it’s likely failed open — replace it. - If you suspect it’s stuck closed (causing overheating), look for continuity when cold (shows closed) AND inspect for burned/chipped housing or melted parts. A thermostat stuck closed may still show continuity; in that case also check thermal fuse and high-limit thermostat and ensure thermostat opens when heated (advanced test using heat gun while monitoring continuity is possible but not necessary for most DIYs). 5) Inspect wiring and connector harness - Look for burned terminals, loose spade connectors, or melted nylon connectors which can cause intermittent contact. 6) Replace the cycling thermostat (if faulty) - Tools: screwdriver, nut driver, needle-nose pliers, multimeter, replacement part WP3387134 or equivalent. - Safety: unplug dryer and shut off gas supply (gas dryer). - Remove access panel to reach the old thermostat. - Photograph wiring layout. Pull off the spade connectors with pliers (do not yank wires). Remove mounting screw(s) and take out the thermostat. - Install new thermostat in same orientation, secure with screws, reconnect wires to the correct terminals. - Reassemble panels, restore power/gas, and run a test cycle to confirm proper heating and cycling. 7) Final checks and test - Run the dryer empty on a timed heat cycle and observe: dryer should heat within a couple of minutes and cycle off/on as temperature is reached. Check vent airflow and drum temperature to confirm normal operation. Safety note: Always disconnect electrical power before servicing. For gas dryers also shut off the gas supply. If you’re uncomfortable working with electrical components or gas systems, hire a qualified technician.
Common Symptoms
Dryer won’t heat at all, dryer overheats or runs too hot, intermittent or inconsistent drying times, dryer cycles heating erratically.
Common Causes
- Cycling thermostat has failed open (no continuity) — no heating
- Cycling thermostat stuck closed — causes overheating
- Damaged wiring or connector at the thermostat
- Restricted venting/airflow causing overheating and damaging the thermostat
Popular Parts That Fix This Problem
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Helpful Repair Tip
Use a multimeter: at room temperature the cycling thermostat should show continuity. If it's open (infinite resistance) it's bad. Also inspect for physical signs—burning, melting, or corrosion—on the thermostat and connectors.
Frequently Asked Questions
How do I test the WP3387134 thermostat?
Unplug the dryer and remove power. Disconnect the thermostat’s wires and use a multimeter on continuity or ohms. At room temperature it should read continuity (near 0 ohms). If it reads open (infinite) it’s failed open and needs replacement. For suspected stuck-closed thermostats, check for physical damage and test alongside the thermal fuse/high-limit thermostat.
Can I replace the WP3387134 myself and how long does it take?
Yes — this is a straightforward DIY repair for someone comfortable with basic tools. Turn off power (and gas for gas dryers), remove the access panel, swap the thermostat, reconnect wires, and reassemble. Typical time: 20–45 minutes. If you’re not comfortable with electrical or gas work, call a pro.
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