Whirlpool WRT318FZDW (Top Freezer) – Frost buildup in freezer Repair Guide

🔧 Step 1: Test defrost heater continuity

1. Unplug the refrigerator from the wall outlet and wait 5 minutes for capacitors to discharge.
2. Open the freezer door and remove all food items, placing them in a cooler with ice.
3. Remove the 4 plastic shelf clips by pulling them straight up and off the wire shelves, then slide out all wire shelving.
4. Locate the back panel inside the freezer compartment—a white plastic panel measuring approximately 24 inches wide by 30 inches tall.
5. Remove the 6 Phillips-head screws (#2 screwdriver) securing the back panel: 2 screws at the top corners, 2 at mid-height on each side, and 2 at the bottom corners.
6. Grasp the panel at the top edge and pull it forward approximately 2 inches, then lift up to unhook the bottom tabs from their slots.
7. Set the panel aside. You’ll now see the evaporator coils (aluminum fins) with a glass tube running horizontally beneath them—this is the defrost heater.
8. Locate the two wire terminals at the right end of the defrost heater tube. They have push-on spade connectors with red and white wires attached.
9. Pull both wire connectors straight off the terminals using needle-nose pliers if needed.
10. Set your multimeter to the ohms (Ω) setting, typically the lowest resistance range (200Ω or similar).
11. Touch one multimeter probe to each metal terminal on the defrost heater.
12. Read the display. A functional defrost heater will show between 28-52 ohms of resistance. An “OL” (overload) or infinite reading indicates the heater is open and failed. A reading of 0 ohms indicates a short circuit.

🛠️ Step 2: Check defrost thermostat

1. Locate the defrost thermostat attached to the evaporator coils in the freezer section, typically mounted on the left side of the coil assembly approximately 8 inches from the top.
2. Unplug the refrigerator from the wall outlet to cut all power to the unit.
3. Remove all items from the freezer compartment and set them in a cooler with ice.
4. Locate and remove the screws securing the rear freezer panel – there are 4 Phillips-head screws along the top edge and 2 along each side, requiring a Phillips #2 screwdriver.
5. Pull the rear panel forward and lift it up to disengage the bottom clips, then set the panel aside.
6. Identify the defrost thermostat – it’s a small white or silver cylindrical component about 1 inch in diameter with a metal capillary tube extending from one end that’s clipped to the evaporator coil.
7. Disconnect the two-wire connector from the thermostat by pulling the plastic housing straight off – note the wire colors (typically white and brown).
8. Set your multimeter to the ohms (Ω) setting at the lowest range (usually 200 ohms or RX1).
9. Touch one multimeter probe to each of the two metal terminals on the thermostat body where the wires were connected.
10. Read the multimeter display – at room temperature (68-72°F), the thermostat should show an open circuit (infinite resistance or “OL” on digital meters).
11. Place the thermostat in a bowl of ice water for 2 minutes to cool it below 32°F.
12. Test again with the multimeter while the thermostat is still cold – it should now show 0-2 ohms of resistance (continuity), indicating the contacts have closed.
13. If the thermostat shows continuity when warm or no continuity when cold, it has failed and requires replacement (part number W10225581).

⚙️ Step 3: Verify defrost timer operation

1. Locate the defrost timer in the refrigerator compartment, bottom rear section, behind the temperature control housing or mounted on the compressor compartment’s left side near the floor (varies by manufacturing date – check both locations on this model).
2. Identify the timer by its square white or cream-colored housing, approximately 2 inches x 2 inches, with a manual advance dial (typically orange or red) protruding from the front and 4 wire terminals on top.
3. Use a flathead screwdriver (1/4-inch blade width) to insert into the white manual advance slot on the timer’s face, then rotate clockwise until you hear a single click (approximately 1/4 turn).
4. Listen at the evaporator section in the freezer compartment – you should hear the compressor shut off within 10 seconds and the defrost heater activate (may hear slight sizzling if frost is present).
5. Wait 20-30 minutes while monitoring – the defrost heater should remain on, and you should see or feel warmth near the evaporator coils behind the back freezer panel.
6. Return to the timer and advance it clockwise again until you hear another click – the compressor should restart within 30 seconds, and the defrost heater should turn off.
7. If the timer does not click, does not advance, or if the compressor does not cycle off and on with each advancement, the timer has failed and requires replacement (part number 482493 or WP482493).
8. If the timer advances but the compressor does not respond, use a multimeter set to continuity mode and test between terminals 1 and 2 (compressor circuit) – you should read 0 ohms or continuity when in cooling mode.
9. Test terminals 1 and 4 (heater circuit) – you should read continuity only when manually advanced to defrost mode.
10. Record whether the timer passed (cycles properly and shows correct continuity) or failed (no advancement, no clicks, or incorrect continuity readings).

🔩 Step 4: Replace faulty defrost components

1. Locate the defrost heater underneath the evaporator coils in the freezer compartment—it’s a glass tube approximately 18 inches long, positioned horizontally along the bottom of the coil assembly.
2. Disconnect the defrost heater by gripping the white plastic wire connectors on both ends and pulling straight apart—these are located at the left and right sides of the heater assembly.
3. Slide the defrost heater out of the two metal mounting clips (one on each end) by lifting upward approximately 1/4 inch, then pulling forward.
4. Remove the defrost thermostat (part number WPW10225581) mounted on the evaporator coil tubing, approximately 8 inches from the bottom left corner—use a flathead screwdriver to pry the metal clip securing it to the copper tubing.
5. Disconnect the two spade terminals from the defrost thermostat by pulling each wire connector straight off.
6. Install the new defrost thermostat by sliding its metal clip onto the same copper tubing location, positioning the sensor body flat against the tubing.
7. Connect the two wire terminals to the new thermostat—push each connector onto the spade terminals until they seat completely with no exposed metal visible.
8. Insert the new defrost heater (part number W10918546) into both metal mounting clips by aligning the glass tube ends with the clips and pressing down until you hear two distinct clicks.
9. Reconnect the white wire connectors on both heater ends—push together firmly until the locking tabs engage with an audible snap.
10. Verify all three defrost components are secure by gently tugging each wire connection—none should separate with moderate hand pressure of approximately 5 pounds of force.

📋 Step 5: Manually defrost freezer

1. Place 3-4 bath towels on the floor directly in front of the refrigerator, extending 2 feet outward to catch melting ice and water.
2. Position two large roasting pans or shallow containers on the freezer floor, one toward the front and one toward the back, to collect water runoff.
3. Remove all frozen food items from the freezer compartment and transfer them to a cooler with ice packs.
4. Locate the freezer drain hole at the back wall of the freezer compartment, centered horizontally and positioned approximately 1 inch above the floor surface.
5. Fill a turkey baster or large syringe with hot tap water (approximately 120-130°F).
6. Squeeze hot water directly onto thick ice buildup on the freezer walls, starting at the top and working downward in vertical sections.
7. Place two pots of boiling water (approximately 4 cups each) on trivets or hot pads on the freezer shelves, then close the door for 10-15 minutes to create steam acceleration.
8. Open the door and use a plastic putty knife (not metal) to gently push loosened ice away from walls, applying pressure parallel to the surface to avoid puncturing the liner.
9. Collect large ice chunks as they fall and place them in the sink or bathtub.
10. Pour 1 cup of hot water directly into the drain hole at the back wall to clear any ice blockage in the drain tube.
11. Wipe down all interior freezer surfaces with a clean towel, removing all moisture and remaining ice particles.
12. Empty the roasting pans of collected water, which should total approximately 2-4 cups depending on ice accumulation.
13. Verify the drain hole is completely clear by pouring an additional ½ cup of water into it and confirming water flows freely without pooling.

⚠️ Safety Reminders

• Always unplug the refrigerator before beginning any repair work
• Allow the unit to warm up if working with frozen components
• Use proper tools and safety equipment
• If you’re unsure about any step, consult a professional

← Back to Top 20 Refrigerators Guide

🛒 Recommended Products

Here are the recommended products for this repair:

• WR51X10055 Refrigerator Defrost Heater Kit,WR55X10025 Temperature Sensor,WR50X10068 Defrost Thermostat Replacement for General Electric Hotpoint Refrigerators Replaces WR51X10030
• Refrigerator Defrost Thermostat W10225581, 2 Pcs Bimetal Defrost Thermostat Exact use for Whirlpool, Sears, Kenmore Refrigerator: Replace
• AP2592907 Refrigerators Defrost Timer for Frigidaire,120V 6 Hour 21 Minutes 215846604 Timer Fits Fridge and Freezers by Ketofa

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