The following troubleshooter is for a GE top-freezer refrigerator, model #GTS16DTNRWW, however, the principles are the same for similar brands and models.
Before beginning work on any appliance, unplug it from its power source. You will need a pair of gloves to protect your hands from sharp edges.
Any work performed on an electrical appliance could be hazardous to your health. If you decide to perform this work yourself, please note that there is some risk of injury. The risk can be reduced by using the right tool, the right safety equipment, and following all directions. You should not proceed if you are not confident or feel in any way incapable of doing the job. Some repairs and maintenance should only be performed by a skilled, trained, and certified technician.
The defrost heater functions to keep the evaporator fins free from frost and ice buildup. If the heater fails to operate, frost will become ice leading to ventilation problems. Eventually, this will lead to a warmer freezer, which is another symptom of a failed defrost heater.
The defrost heater is located behind the evaporator which is located behind an access panel to the rear of the freezer. Click on the link for a quick tutorial on how to remove it.
Once you have the heater removed, you can test it for continuity with a multimeter.
The thermostat monitors the temperature of the evaporator coils. When the temperature drops down to a certain level, the thermostat sends a message to the heater to kick on. When the defrost process starts, all other components in the refrigerator such as the compressor are turned off. You may hear a sizzle as the heater begins its work of melting frost from the evaporator.
A thermostat not working correctly will prevent the heater from working properly.
The thermostat can be tested with a multimeter for continuity. However, be aware that this part needs to be tested at 15° Fahrenheit or lower.
Some models come equipped with a timer. The timer functions to turn on the heater for 25 minutes, two or three times a day. A malfunctioned timer will prevent the cycle from completion and the heater may not have turned on to begin with.
The timer can be tested by slowly advancing it to the defrost cycle. If the timer is working properly, the compressor should turn off and the heater should turn on.
If advancing the timer does not turn on the heater or if the timer does not advance out of the defrost cycle within 30 minutes, the timer should be replaced.
Defrost Control Board
On some models, a control board controls the defrost cycle. A timer is not needed. While control boards can develop their own set of problems, it is not usually a bad control board causing defrost problems. However, if after testing the defrost heater, defrost thermostat, timer, and all have tested positive, then it’s time to take a look at the control board.
Inspect the board for any burn marks, cracks, warps, or any other distortions. Replace the board if you find anything that reflects some type of damage.
Freezer Door Gasket
Perhaps I should have placed this troubleshooter at the top of the list as it is the easiest one to check. But even after you run this test and you find that you need to replace the door gasket, you won’t really know if you’ve solved your defrost problem until after you troubleshoot the above components.
If air is leaking from the freezer compartment, the defrost heater will not be able to keep up with the additional demand to maintain a chilly 0°.
How to Test the Door Gasket
- Open the freezer door.
- Place a dollar bill on the door gasket and close the door.
- Try to pull the dollar bill out. If the seal is good, you shouldn’t be able to remove it.
- In order for this to be an accurate test, try the dollar bill test at several locations around the freezer door.
- If you are able to remove the bill, the gasket needs to be replaced.