Dryer Cycling Thermostat (Internal Bias L155-25) (Whirlpool OEM)

Description

Genuine Whirlpool OEM Dryer Cycling Thermostat (Internal Bias L155-25) – Part WP3387134

Part Number: WP3387134

Replaces: AP6008270, 3387134, 3387135, 3387139, 306910, ET187, WP3387134VP, PS11741405

Always verify compatibility using your appliance model number before ordering.

Whirlpool Dryer Operating / Cycling Thermostat (Part # WP3387134)

Maintain perfect heat management and prevent structural overheating in your laundry room with this Genuine OEM Whirlpool Dryer Cycling Thermostat. This factory-certified safety component (Part # WP3387134, which directly replaces standard factory configurations like 3387134, 3387139, AH11741400, and EA11741400) is the primary climate-control brain regulating your appliance’s internal air temperature.

Mounted directly onto the internal blower wheel scroll housing, this bi-metal switch continuously samples exhaust air temperatures. When the drum reaches its optimal target drying temperature—typically around 150°F (65°C)—the internal electrical contacts inside this thermostat click open, cutting power to the gas burner valve or electric heating element. As the air naturally cools down, the contacts snap shut again, re-energizing the heat source. This continuous cycling loop keeps your clothes drying efficiently without shrinking or scorching your delicate fabrics.

If this part fails, it typically leaves its contacts permanently stuck open or permanently stuck closed. This causes severe failure symptoms, including a dryer that tumbles continuously but stays completely cold, or a dryer that overheats drastically and blows your one-time thermal safety fuse.

Quick Info:

• Compatibility: Precision engineered for Whirlpool, Kenmore (110-Series), Maytag, Amana, KitchenAid, Jenn-Air, Admiral, Roper, and Estate clothes dryers.

• Electrical Specifications: Rated at a baseline operational temperature of 155°F (68°C) with an internal internal bias heater circuit (incorporating an extra set of small terminal leads to lower the cycling temperature for “Low Heat” or “Delicate” fabric settings).

• Fixes Common Issues: Resolves “no heat” or “low heat” conditions, infinitely long dry times, extreme cabinet overheating, and premature thermal fuse failures.

• Difficulty: Novice to Intermediate. A highly straightforward DIY repair requiring basic nut drivers and access to the lower rear or lower front cabinet compartment.

Pro Tip: If your dryer suddenly stops heating altogether, you can easily verify whether this cycling thermostat or your primary thermal fuse is the culprit using a basic digital multimeter set to Ohms ($\Omega$) / Continuity mode. First, disconnect the wire leads from the thermostat terminals. Touch your meter’s test probes directly to the two larger primary brass terminals. A healthy thermostat at room temperature should read 0 Ohms (or emit a continuous beep), indicating a complete, closed electrical path. If your meter screen reads “OL” (Open Loop) or shows infinite resistance while the part is cool, the internal bi-metal disc has fractured, and the part is defective.

Installation & Safety Steps:

1. Isolate Power: You must completely unplug the dryer’s power cord (or shut off the main dual-pole house circuit breaker) to eliminate the risk of high-voltage shocks while handling raw electrical spade terminals. If it is a gas model, shut off the gas supply line valve as an added safety measure.

2. Access the Blower Shroud: Depending on your specific model framework, pull off the lower rear metal access panel, or dismantle the lower front cabinet kick-plate panel underneath the door to reveal the plastic blower scroll housing.

3. Label and Unplug the Leads: This thermostat features a 4-wire terminal configuration (two large primary heat terminals and two smaller auxiliary bias-heater terminals). Take a quick picture with your phone before unplugging the wires to ensure you don’t mix up the positions on reassembly. Pull the spade connectors straight off the prongs using needle-nose pliers.

4. Swap the Assembly: Unthread the mounting screws holding the oval metal mounting flange to the housing wall. Pull out the old thermostat, wipe any accumulated lint off the seating port, screw the new genuine factory part tightly into place, and slide the wire leads firmly onto their matching terminals.

Are you replacing this cycling thermostat today because your dryer has stopped heating entirely, or did your appliance recently overheat and blow the main thermal fuse?