How to Replace the Defrost Sensor in a LG Refrigerator

During the defrost cycle in a LG refrigerator model LFX21976ST, the defrost sensor tells the main control board the temperature inside the freezer. When the sensor is defective, the defrost cycle may stop functioning, which ultimately causes the evaporator in the freezer to ice up and the temperature in the fresh food compartment to increase. If your appliance is showing symptoms of a faulty defrost sensor, don’t worry, the step-by-step guide provided below will help you replace the malfunctioning part.

How to Replace the Defrost Sensor in a LG Refrigerator

Before starting any type of repair, unplug your appliance. If you can’t move your appliance to reach the outlet, turn the electricity running to it off at the circuit breaker. Always wear work gloves and safety goggles to protect your hands and eyes from injury.

  1. Start the repair by opening the freezer door and removing the lower frozen food bin. Lift the back of the bin up to release the locking tabs. With the back angled up, pull the front end of the bin out of the freezer.
  2. Now remove the door assembly from the freezer rails. Locate the two screws on the side of the rails which hold the assembly and rails together. Take the screws out with a Phillips screwdriver. Once both screws are removed, lift up on the door assembly to disengage the four locking tabs, and then pull the door and frame off the rails and place it in a safe area.
  3. Push the rails back into the freezer, and pull the upper basket out. Depress the two tabs on the front of the basket to release it from the rails. Angle the front of the basket up before lifting the entire assembly out of the freezer. Push the rails back into the compartment.
  4. With the racks out of the way, it is time to remove the rails. Using a Phillips screwdriver, take out the screws from the upper rail, first. After the screws are removed, pull the rail off the freezer wall. Repeat the same process on the other side.
  5. Now move on to the bottom rails. Start by pulling the rails out of the compartment to gain access to the connecting rod in the back that links the left and right rail. To disconnect the rod, release the locking tab situated between the gear wheel and the mounting plate. Once you have the first side off, simply pull the other side out of the opposite gear wheel. Push the rails back in, and use a Phillips screwdriver to remove the rails from the freezer walls.
  6. With the rails out of the way, you can take out the freezer’s back panel. First, with a putty knife, open up the small rectangular access cover located in the upper right hand corner. Insert the putty knife into the small gap in between the cover and rear panel to disengage the locking tabs keeping them connected. Take out the small access cover and set it aside. To remove the rear panel, reach into the opening you created and find the locking tab connecting the back panel to the freezer compartment. Once that tab is released you can start pulling off the panel. When all the tabs are disengaged, lower the panel down to the freezer floor, and disconnect the two wire harnesses linking the rear panel to the back wall. Now you can pull the rear panel out of the freezer.
  7. You have finally gained access to the defrost sensor, which is located near the top right side of the evaporator. It is important to be extra careful while taking the sensor out. Damaging the evaporator coils or fins can lead to a Freon leak, which can only be fixed by a professional. To begin the removal process, cut off the three zip ties holding the defrost sensor in place. Once all the zip ties are gone, you can take the defrost sensor out by first extracting the thermistor at the bottom and then pulling out the fuse from the top. When those two sections are free, you can disconnect the wire harness from the back wall of the freezer. Then carefully take the defrost sensor out of the freezer compartment.
  8. Before installing the new defrost sensor, guide the upper zip tie through the hole in the evaporator, so you can secure the sensor once you have it connected. Now run the defrost sensor wire harness behind the copper line and plug it into the freezer’s back wall. Route the wires along the side of the evaporator. Once the sensor is in place, secure it with zip ties at the top, middle and bottom. Make sure to trim the zip ties after you have tightened them.
  9. It’s time to begin reassembling your freezer compartment. Plug the two wire harnesses attached to the rear panel into the freezer’s back wall, and reinsert the panel by snapping it into place. Now reinstall the small rectangular access cover.
  10. Reattach the bottom two rails on each side of the compartment. After you have secured them with the screws you took out earlier, you can move on to the top two rails. Once you are finished with all four rails, slide the bottom rail out of the freezer and reattach the connector rod.
  11. Finally, you can put the freezer door back on. To do, line up the tabs in the door rails to the holes in the freezer rails, and lower the door assembly down until it snaps into place. Once the door is in place, perform a quick test by pushing the door in and out to ensure it opens and closes properly. If it does, you can put the screws in that holds the door to the rails.
  12. To complete your repair, pull out the top rails and insert the freezer basket and then push the basket back into the compartment before reinstalling the bottom bin. Now that the refrigerator is reassembled, plug it back in and enjoy your properly functioning appliance.
If your newly installed defrost sensor did not correct your refrigerator’s problem, please contact us today to schedule an appoint with one of our highly qualified appliance repair technicians.