How to locate and replace defrost timer. Seems to stick in defrost mode.

Hello Santiago;

My name is Peter. I am a retired field service refrigeration technician.

In the defrost mode everything shuts down with the exception of the light.

So, lets trip the defrost timer and get your freezer running.

You did not provide a model number which is located on a label on the inside liner wall near the top.

Your defrost timer may be part of your control board.

Let's assume it is not.

In the lower back left hand corner of you unit the is a metal plate with a small slotted shaft. With a large flat head screw driver turn the shaft clockwise on click at a time until your unit starts up. You must do the same thing every 12 hours to turn it off for 30 minutes to allow for defrost until the timer is replaced is replaced.

Note the round on the left.

Go into the following web site, put in your model number. Select the diagram with the defrost timer. Search the internet with the part number shown
Water Filters Lawn Garden Appliance Parts

Yup, these timers have a tiny clock motor that can get lint on them, causing motor failure, should be simple replacement. Refrigerators in cold garages run more to regulate their temperature below 45 degrees.

It could be stuck in defrost mode. However if you can locate the defrost timer pictured here:
You can advance to turn on controls, compressor. If it sticks it should be replaced.

DEFROST PROBLEM
The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can't flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad, it can prevent the heater from coming on OR it won't turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass(disconnect the two wires plugged into it and twist them together) the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it's bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it's in the defrost mode.

If you have a defrost timer you can test it. It can be located under the fridge behind the kick panel on the front. Some are in the fridge with the controls at the top. You can turn the defrost timer till it clicks and everything shuts down. The heater should now come on. If it does, replace the timer because that means the timer is not running. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.

If you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good. It is located in the fridge with the controls in some models and on the back in others.

It sounds like you have a failure of the automatic defrost system. This system has 3 components

- timer, this device provides power to the compressor for cooling then changes to the defrost mode every 8 - 10 hours and provides power for the heater

- heater, this is located just below the evaporator and clears the frost from the coils

- terminator, this device turns the defrost cycle off and prevents over heating during the defrost cycle.

To test the components locate the timer, it is usually on the back or in front behind the kick panel; it looks like this


The white piece can be turned either by hand or a flat blade screwdriver, turn it clockwise slowly until a positive 'click' is heard. Once you hear this stop and wait, you will be in the defrost cycle, if you open the door after about 5 minutes you should hear the water sizzling on the heater faintly behind the back panel inside the freezer. If you do hear that then the heater and terminator are okay and you need to replace the timer.

If you do not get heat you will need to unload the freezer, and remove the back panel. Behind there is the evaporator and below that is the heater. You will have to test the heater with an ohm meter it should read under 100 ohms.

The terminator is clipped to the top of the evaporator and should read 0 ohms when it is cold.

I

If the defrost timer sticks in the defrost mode,yes. Normal defrost time is 30 minutes or less depending upon which timer is installed.
If it happens again,locate the defrost timer and turn the dial manually to see if the compressor comes back on. If so,replace the timer.
It is probably on the rear near the compressor. Some are under the front behind the dust guard.

The evaporator coil behind the cover on the back wall inside the freezer will ice up under normal conditions. Every 8 to 10 hours for around 20 minutes the defrost timer (or in most newer models the electronic adaptive defrost control) will turn the defrost heater on to melt the built up ice. There is a defrost thermostat which prevents the heater from overheating the freezer by breaking the heater circuit when the temp reaches close to 32 degrees F. The entire cooling system shuts off during the defrost cycle and starts back when the timer advances through the cycle.

If this ice is not melted it will continue to build up until the air can’t flow over the coil to circulate the cold air through the freezer and into the fridge. The temperature change in the fridge is usually noticed first followed by the freezer.

If the defrost thermostat is bad it can prevent the heater from coming on OR it won’t turn the heater off when it gets too warm. It is clamped to the evaporator coil at the top to sense the temp. If it appears to be misshapen it is bad.
With an ohm meter it should show continuity when cold and none when warm.
You can also bypass the thermostat to see if the heater comes on then. If it does then you know the thermostat is bad and needs replaced.

The defrost heater is located on the evaporator. It is in a tube which is at the bottom and can also go up the sides of the evaporator. On some types you can see a burnt spot if it’s bad. With an ohm meter it should show continuity from end to end when disconnected from the wiring in the freezer. You can also test the wiring for voltage when it’s in the defrost mode.

If you have a defrost timer you can test it. It can be located under the fridge behind the kick panel on the front. Some are in the fridge with the controls at the top. You can turn the defrost timer till it clicks and everything shuts down. The heater should now come on. If it does, replace the timer because that means the timer is not running. If it doesn't, check the heater and defrost thermostat. Turn the timer again till everything starts back up to end the defrost cycle.

If you have an adaptive defrost control instead of a timer, replace it if the heater and thermostat test good. It is located in the fridge with the controls in some models and on the back in others.

If you need help finding your model number see here> http://www.appliancepartspros.com/modelnumber_locator.aspx

To locate your timer, motherboard, control or adaptive defrost control , enter your model number and search for the part or post back on Fixya.
http://www.searspartsdirect.com/partsdirect/index.action?psid=26129238&sid=PSx20071217x00001a

you might have a defrost problem. Frost free models have a heating element that is controlled by a timer to automatically defrost ice, defrost timer turns on defrost heating element every 12 hours to melt ice in freezer and allow good air flow.
You can test defrost element with an ohm meter(located inside freezer coils-will have two wires going to a plug connection), if OK replace defrost timer (located in various places depending on make and model

Hi!

Thanks for using FixYa. First of all please check that there is air flow in the upper vent baffle in the fridge section which is located behind the crispers. If there is no air flow at the vent baffle in the upper fridge section then this is the cause of the issue you’re facing with. The evaporator fan pushes the air through ducting into the refrigerator from the freezer and if there is any material obstructing it then clear it.

If still the problem persists then you need to check the following things:

The defrost circuit contains defrost timer, defrost heater(s) and defrost thermostat. Defrost timer failure will not put power to the circuit. Defrost heater failure will fail to defrost when the timer applies power. Defrost thermostat must be closed for defrost to take place. First locate the timer, rotate the clutch head screw clockwise slowly until one distinct click is heard. Now the timer will be set in defrost mode and defrost should complete within 30 minutes or less after which the refrigeration should start cooling again. If defrost takes place and it does not go back to cooling automatically turn the screw once again until you hear the second click, unit will start. Replace the timer. If defrost does not take place in the time frame above and the unit restarts in cooling test the defrost heaters. From the heater(s) follow the wires from each end to where they plug into the circuit. Unplug them and test through the heaters with an ohm meter. You should get a reading if they are good, if no reading then you need to replace the heater(s). If you get a reading on the heater(s) then you need to replace the defrost thermostat.

Please do rate the solution and revert for further assistance.

Thanks
Rylee

If this is a frost free unit as I received it posted you may have a problem in that it is not frost free. The cooling coil may be frozen over stopping air circulation. There would be a defrost timer located somewhere in back. Located the clutch head screw and turn it clockwise SLOWLY until you hear one audible click. That should put the system into the defrost mode. Wait about 30 minutes in which time the system should return to the cooling mode (usually 18-22 minutes). If it does not restart the compressor after that time turn the clutch head screw clockwise again and it should restart. If you had to turn the screw the second time it would indicate a bad defrost timer. In this case replace the timer.