The third pair of terminals should show no continuity (infinity).
We will attempt to explain the workings using simplified electrical schematics.The heart of the defrost system is the defrost control. The most common control is a mechanical defrost timer which is a motorized device that opens and closes several electrical contacts.
Copyright © 2000 - 2020, Acme Parts.com, Inc. All rights reserved. On this system only the defrost heater is the same as described above. Remove the screws and gently pull the timer out far enough to disconnect the wiring connector. For these isolated cases, this was reported to be the correct operation of the timer. If it does not advance, the timer motor is probably bad and the entire timer needs to be replaced. once you have the cover off and the defrost timer unscrewed you must remove a plug from the timer! It very well could be your defrost timer or "adaptive defrost control board". Defrost timers almost always have four metallic terminals extending from the bottom. The defrost timer is the brain of the automatic defrost system. One pair of terminals should indicate continuity (possibly two pairs). It was in this repair. The defrost timer is usually found behind the front grill "toe kick" of the refrigerator. Simply wait about 35 minutes and check whether it has left defrost mode and has resumed cooling (listen for the compressor). For these, check the appliance's ' It may also be found behind a cover plate inside the refrigerator or freezer, in the temperature control console, or behind the refrigerator near the compressor.To test whether the defrost timer is simply failing to advance, locate the advance screw and turn it clockwise until you hear it click. Frost may also be visible on the panel covering the evaporator, usually in the rear of the freezer compartment.Excessive frosting can be cause by the defrost heater or limit thermostat being open (ie. These timers were installed in a way were they would only count the time that the refrigerator (the compressor) was actually working. When one of these is switched on, the other is switched off. Modern refrigerators have a defrost function with a defrost timer, thermostat, heater, and drain, combined with an evaporator fan motor.You may need to test your defrost timer at some point. Touch the other probe to each of the three remaining terminals. Remove the back or bottom panel using a Phillips screwdriver to expose the defrost timer. Also, note that this article applies to mechanical defrost timer controls and not electronic or adaptive defrost controls. If either of those components should fail, remaining open, the fan will not run which will stop the circulation of cold air throughout the refrigerator.On that design, the evaporator fan motor will not start running after a defrost cycle until the evaporator has had a chance to begin cooling again. The control can not be manually put into defrost mode. This makes sense since no frost could build up if the compressor was not running.These later mechanical model timers would only advance the into defrost when the compressor had actually been running for a certain length of time, usually 6 to 8 hours of accumulated compressor operation.Newer GE made refrigerators are almost totally electronically controlled. Assemble the timer back onto the fridge and reinstate the power supply. Test points and how to manually switch adaptive defrost controls into the different cycles vary from manufacturer to manufacturer. If the defrost timer does not pass these tests, it is likely that it should be * We have received two reports of cases in which only one pair of terminals shows continuity and when the timer is advanced, the same pair still shows continuity. cold control) cycles the compressor and fan motors on and off to maintain an appropriate temperature. The termination thermostat on this appliance design only acts as a safety device to shut the heater(s) off in case of a malfunction before the plastic interior liner melts, otherwise it is never active. Video describing how to test the defrost timer on your refrigerator. A motor on the timer (NOT illustrated) turns a cam that opens and closes these contacts at set intervals (see below for other types).While in this mode, the thermostat (a.k.a. This can result in thawing then refreezing of food in the freezer compartment often leading to freezer burn on that food. The defrost timer eventually switches into defrost mode and supplies power to the defrost heater(s) to melt any frost that has accumulated on the evaporator (cooling) coil.
Contact us to obtain Each contact can be thought of as a simple light switch but instead of a light, one connects the defrost heater circuit, another connects the cooling system. Remove all the screws you find and pull the timer carefully out of the refrigerator. While it is generally a good design idea so as not to blow the warm defrost air throughout the refrigerator, a failure in one part of the defrost system will usually render the whole refrigerator ineffective because of the lack of air flow.The next design was called a 'cumulative run' timer. I also decided to change the defrost timer which is located inside a cover where the frig temperture setting dial is located. The cold control contacts remain closed but since the defrost timer is no longer feeding power to that circuit, the compressor does not run. The freezer fan motor is usually in the same general area.The defrost heater is basically a wire filament enclosed in a quartz, glass, aluminum or other material, tube sheath which gets hot when powered. If it was cooling before, it is now in defrost mode. This may indicate a specific model or models that use a different wiring configuration than discussed in this article. How much resistance it has is irrelevant as its resistance will not normally change except to being open (infinite resistance) when it fails.The defrost termination thermostat (aka defrost limit switch) is basically a small SPST (single pole) electrical switch which is actuated by temperature. A defrost cycle is ended when a thermistor detects a temperature rise of the evaporator which is the signal to the main control to terminate the defrost and start the cooling. The timer will be on the back or the bottom of your model. Step 2 Turn the notch located on the face of the defrost timer counterclockwise until it is turned completely. Their motherboard takes the place of both the temperature and defrost functions even controlling DC fan motors that can operate at several different speeds.