Ice Build up on back panel of top freezer.

You didnt give the make of the ref.; But your solution is here for most all

The newest defrost feature in modern fridges is the electronic adaptive defrost control board. *Maytag has one version, see picture...to put this adaptive defrost style of fridge into defrost, short with a small screwdriver between L1 and test on the adaptive defrost board, wait 3 seconds and you should hear a "click" noise from the relay and the fridge will shut off and go through a defrost cycle. A close up common way *this* version of the Maytag/JennAir control is wired.
Amana also has a version of adaptive defrost, see info sheet for some help on the Amana version. Press refrigerator light switch five times in six seconds to initiate defrost cycle. Pressing five more times within six seconds will cancel defrost and go straight into the run mode. Similar operation on both bottom mount and SxS refrigerators. After the defrost terminator/thermostat opens, six minutes of dwell time occurs before the compressor and condenser fan motor will operate. After defrost terminator/thermostat open, 10 minutes of dwell time occurs before the evaporator fan motor will operate.
Frigidaire has also jumped into the market with an adaptive defrost board. The fresh food section light switch and light bulb must work. To initiate a defrost cycle, open the door and push the light switch in and out 5 times within 6 seconds. The compressor and fans should shut off and the defrost heater should come on. Open the door and push the light switch in and out 5 times within 6 seconds to remove the refrigerator from the defrost mode and back into a cooling mode.
Frigidaire - referance model FSC23F7DSB3
This product comes equipped with an Adaptive Defrost Control (ADC). To activate manual defrost, press and hold the Freezer temperature UP (WARMER) key while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds. A ?¿½d?¿½ in the freezer temperature window and ?¿½F?¿½ in the refrigerator temperature window will display when the heater is activated. To deactivate manual defrost, press and hold Freezer temperature UP (WARMER) key while pressing the Fresh Food temperature DOWN (COLDER) key 5 times within 6 seconds. ?¿½d?¿½ and ?¿½F?¿½ will be displayed until the defrost cycle is complete. (approx. 8 minutes)
For some Whirlpool refrigerators - some Kenmore refrigerators are made by Whirlpool ( 106.######## )
The refrigerator/freezer defrost system can be checked by manually initiating a defrost cycle. There
are two methods of initiating the ADC Test Mode.
First Test Method:
1. Turn the thermostat off for 15 seconds.
2. Turn the thermostat on for 5 seconds.
3. Turn the thermostat off for 15 seconds.
4. Turn the thermostat on for 5 seconds.
5. Turn the thermostat off for 15 seconds.
6. Turn the thermostat on for 5 seconds.
7. Turn the thermostat off.
In 3 to 8 seconds the ADC should turn on the defrost heater (with the bimetal closed). NOTE: The test mode will terminate when the bimetal opens. If the refrigerator/freezer is already in defrost, Test Mode can be terminated by unplugging the refrigerator/freezer from the wall outlet and waiting 30 seconds before plugging it back in. The refrigerator/freezer should immediately go into cooling mode if the thermostat is closed.
If this first test procedure fails to make the ADC initiate a defrost cycle, try the following procedure to make the ADC begin the Test Mode.
Second Test Method:
1. Disconnect the refrigerator/freezer from the wall outlet for at least 30 seconds.
2. Turn the thermostat off.
3. Reconnect power to the refrigerator/freezer.
Within 3 to 8 seconds the ADC should turn on the defrost heater (with the bimetal close). If the unit fails to go into the defrost mode during this test, the problem may not be with the ADC. A defective bimetal may be the cause of the failure. The ADC will only go into a test mode if the bimetal
is closed. If the ADC senses an open bimetal it will return to the cooling mode within 3 to 8 seconds.
HELPFUL HINT: Upon entering the Test Mode, the relay mounted on the ADC board should turn off the compressor and turn on the defrost heater. Listen for the relay to click.
?¿½ If the relay clicks one time when entering the Test Mode, check for continuity in the defrost heater.
?¿½ If the relay clicks two times, check for an open bimetal.

Maytag S-S Refrigerator MSD2756GEW forcing defrost cycle
I replaced my defrost heater two weeks ago, but the frost built back up on the evaporator coils. Replaced the adaptive defrost board with new ( Maytag p/n 6100598 8 ) board. Want to force a defrost cycle to see the heater work, so I shorted the L1 pin to adjacent pin (now called DOOR instead of TEST) for three seconds and nothing happens. Compressor keeps running, fans still going etc. Tried pressing the door switches 5 times in 6 seconds and that doesn't work either. Any hints on how to get the defrost cycle to initiate?
Hi,
This might help, a copy:
The issue is that some 12002104 ADC boards have been shipped in the 61005988 ADC board box. Do not reorder the board, the 12002104 board will function the same in place of the 61005988, but you must use the forced defrost method for the 12002104. Jumping "L-1" and "door" will not initiate the forced defrost function.
To Initiate Forced Defrost Cycle:
Cycle cold control on and off three times in six seconds. The cold control needs to be left in the closed (call for cooling) position for the defrost system to energize on all platforms. It is not enough to cycle the cold control knob, the contacts must actually open and close (open doors for a period of time if necessary to force the control to call for cooling). In most cases, you can hear the contacts open and close if they are doing so.
To Terminate Forced Defrost Cycle:
Disconnect power for five seconds.
You were right. I cycled the cooling controls three times and it went into a defrost cycle. Thanks.

KentC, This was my post on a model like yours.  Read thru this and let me know what you find.   If the ice/frost buildup is fairly thick and only on the back freezer panel then you have a defrost problem. Most likely the defrost thermostat is bad. It would be hard to explain how to test this in writing but there is a tech sheet underneath the fridge behind the grill on the r/f. It is in plastic which is stuck to the fridge. This tech sheet will tell you how to put it into diagnostic mode. First take the back panel of the freezer off (may need to get frost off first). Should be four 1/4" screws in each corner of the panel to remove. Will need to remove racks, door (should just lift off), and ice maker first. Remove vent in center of freezer panel by pushing up little tab in the center of the vent and using a screw driver to pop it loose on each side of the vent. Then remove thermistor cover on right hand side of panel. Remove (by pushing thru) ice maker plug. Once the panel is off put the fridge into defrost by the instructions on the tech sheet. If it goes into defrost (heater will get hot) then the main control board is bad. If not shut the doors to reset, defrost evaporator with a hair dryer and remove the defrost thermostat. It is a little metal round piece with two wires coming out of it and just clips onto the evaporator. Cut the two wires coming out of the thermostat, strip them back and splice them together. Now put it into defrost again. If the heater comes on then you know the thermostat is bad. Diagnostics mode can also test all functions i.e. condensor motor, compressor, evaporator fan, and thermistors. With all of that said, if it isn't a thick frost buildup the evaporator fan motor may be bad which is the most common repair on this model. It sits just behind the vent in the center of the freezer panel. Let me know what you find.

If the ice/frost buildup is fairly thick and only on the back freezer panel then you have a defrost problem. Most likely the defrost thermostat is bad. It would be hard to explain how to test this in writing but there is a tech sheet underneath the fridge behind the grill on the r/f. It is in plastic which is stuck to the fridge. This tech sheet will tell you how to put it into diagnostic mode. First take the back panel of the freezer off (may need to get frost off first). Should be four 1/4" screws in each corner of the panel to remove. Will need to remove racks, door (should just lift off), and ice maker first. Remove vent in center of freezer panel by pushing up little tab in the center of the vent and using a screw driver to pop it loose on each side of the vent. Then remove thermistor cover on right hand side of panel. Remove (by pushing thru) ice maker plug. Once the panel is off put the fridge into defrost by the instructions on the tech sheet. If it goes into defrost (heater will get hot) then the main control board is bad. If not shut the doors to reset, defrost evaporator with a hair dryer and remove the defrost thermostat. It is a little metal round piece with two wires coming out of it and just clips onto the evaporator. Cut the two wires coming out of the thermostat, strip them back and splice them together. Now put it into defrost again. If the heater comes on then you know the thermostat is bad. Diagnostics mode can also test all functions i.e. condensor motor, compressor, evaporator fan, and thermistors. With all of that said, if it isn't a thick frost buildup the evaporator fan motor may be bad which is the most common repair on this model. It sits just behind the vent in the center of the freezer panel. Let me know what you find.

HI. There are two causes here, in this situation. The most common will be a faulty defrost timer, or adaptive defrost control board. The defrost mechanism will vary form unit to unit. Most newer units will be equipped with an defrost control board. This will be located in the control housing, just above the heat shield, in the upper right had side. Older models will have a standard defrost timer mechanism. If this device fails, the evaporator heater Assembly will not receive the command to defrost the coil, on time. The easiest way to isolate the cause, will be to test the heater element. If the element is functional, the defrost timer/board, will be the culprit.

Defrost heater assembly test procedure:

The defrost heater is usually located at the back of a side by side freezer or under the floor of a top freezer. It will be necessary to remove obstructions such as the contents of the freezer, freezer shelves, ice-maker and the inside rear or bottom panel of the freezer, to access.

The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky, so try not to force it, if possible. If you decide to remove it, you do so at your own risk. it will break, if forced. Warm it first with a warm towel, or hair dryer, set to low heat.

There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way.

The heater is connected by two wires. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced.

Test the heating element for continuity using a multimeter. Set the multimeter to the ohms setting X1. Place a probe on each terminal. The multimeter should display a reading somewhere between zero and infinity. Because of the number of different elements we cannot tell what your reading should be, but we can be certain of what it shouldn't be. If the reading is zero or infinity the heating element is definitely faulty, and should be replaced.

HI. There are two causes here, in this situation. The most common will be a faulty defrost timer, or adaptive defrost control board. The defrost mechanism will vary from unit to unit. Most newer units will be equipped with an defrost control board. This will be located in the control housing, just above the heat shield, in the upper right had side. Older models will have a standard defrost timer mechanism. If this device fails, the evaporator heater Assembly will not receive the command to defrost the coil, on time. The easiest way to isolate the cause, will be to test the heater element. If the element is functional, the defrost timer/board, will be the culprit.

Defrost heater assembly test procedure:

The defrost heater is usually located at the back of a side by side freezer or under the floor of a top freezer. It will be necessary to remove obstructions such as the contents of the freezer, freezer shelves, ice-maker and the inside rear or bottom panel of the freezer, to access.

The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky, so try not to force it, if possible. If you decide to remove it, you do so at your own risk. it will break, if forced. Warm it first with a warm towel, or hair dryer, set to low heat.

There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way.

The heater is connected by two wires. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced.

Test the heating element for continuity using a multimeter. Set the multimeter to the ohms setting X1. Place a probe on each terminal. The multimeter should display a reading somewhere between zero and infinity. Because of the number of different elements we cannot tell what your reading should be, but we can be certain of what it shouldn't be. If the reading is zero or infinity the heating element is definitely faulty, and should be replaced.

I have some information on your model and that would involve forced defrost by the service manual page 28 at bottom. How old is your Samsung? Forced Operation Function (Pull-down / Refrigerator Defrost / Refrigerator . Freezer-Defrost / Cancellation)
● This function enables a pull-down mode, a defrost mode for the refrigerator only, a defrost mode for the freezer and the
refrigerator at the same time, and a cancellation of this function.
● Press Power Freeze and Fridge Temp. buttons for 8 seconds simultaneously to get in the ready mode for a forced
operation.
● The display panel will return to normal after 20 seconds in the ready mode.
● At the ready mode, press any button(except Ice Type and Child Lock) once to start a pull-down operation, twice for a
defrost cycle for the refrigerator, three times for a defrost cycle for the freezer and the refrigerator, and finally four times
for cancellation of this function.
● Another way to cancel this function is to simply plug out and in the power cord.
1) Pull-down
1-1) At the ready mode, press any button once then the buzzer will beep (ON for 1/2 second and OFF for 1/2 second)
until this mode is cancelled.
1-2) At this pull-down mode, the compressor will start immediately (No 5 minute delay) and if the system is in the
defrost cycle, it will be cancelled right away.
note) If this pull-down mode begins right after the compressor was off, the compressor may not start to run due to an
overload condition.
1-3) At this mode, the compressor and freezer fan will operate continuously for 24 hours and the refrigerator fan will be
on and off according to the set temperature(34℉)
1-4) After 24 hour operation, the system will be cycled at -14℉ for the freezer and 34℉ for the refrigerator.
1-5) In order to cancel this mode at any time, select the next mode on the ready mode or power off the system.
2) Refrigerator Defrost / Refrigerator . Freezer-Defrost operation
2-1) At the pull-down mode, press any button again on the ready mode to begin the defrost cycle for the refrigerator.
2-2) The beep sound continues for 3 second at the beginning, then ON for 3/4 seconds and OFF for 1/4 second until
this mode cease.
2-3) After this operation, the system will come back to normal operation.
2-4) At this mode, press any button again on the ready mode to operate the defrost cycles for both compartments.
2-5) The beep sound continues for 3 seconds at that time, then ON for 1/4 second and OFF for 3/4 seconds until the
defrost operation cease.
3) Cancellation
3-1) At the R,F-Defrost mode, press ant button again on the ready mode to return to a normal operation.
3-2) Simply unplug the power cord, then plug it again to return to a normal operation.
Press both button for 8seconds at the same time Send maual in one moment, Thanks, Sea Breeze

HI. There are two causes here, in this situation. The most common will be a faulty defrost timer, or adaptive defrost control board. The defrost mechanism will vary form unit to unit. Most newer units will be equipped with an defrost control board. This will be located in the control housing, just above the heat shield, in the upper right had side. Older models will have a standard defrost timer mechanism. If this device fails, the evaporator heater Assembly will not receive the command to defrost the coil, on time. The easiest way to isolate the cause, will be to test the heater element. If the element is functional, the defrost timer/board, will eb the culprit.

Defrost heater assembly test procedure:

The defrost heater is usually located at the back of a side by side freezer or under the floor of a top freezer. It will be necessary to remove obstructions such as the contents of the freezer, freezer shelves, ice-maker and the inside rear or bottom panel of the freezer, to access.

The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky, so try not to force it, if possible. If you decide to remove it, you do so at your own risk. it will break, if forced. Warm it first with a warm towel, or hair dryer, set to low heat.

There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way.

The heater is connected by two wires. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced.

Test the heating element for continuity using a multimeter. Set the multimeter to the ohms setting X1. Place a probe on each terminal. The multimeter should display a reading somewhere between zero and infinity. Because of the number of different elements we cannot tell what your reading should be, but we can be certain of what it shouldn't be. If the reading is zero or infinity the heating element is definitely faulty, and should be replaced.

HI. There are two causes here, in this situation. The most common will be a faulty defrost timer, or adaptive defrost control board. The defrost mechanism will vary form unit to unit. Most newer units will be equipped with an defrost control board. This will be located in the control housing, just above the heat shield, in the upper right had side. Older models will have a standard defrost timer mechanism. If this device fails, the evaporator heater Assembly will not receive the command to defrost the coil, on time. The easiest way to isolate the cause, will be to test the heater element. If the element is functional, the defrost timer/board, will eb the culprit.

Defrost heater assembly test procedure:

The defrost heater is usually located at the back of a side by side freezer or under the floor of a top freezer. It will be necessary to remove obstructions such as the contents of the freezer, freezer shelves, ice-maker and the inside rear or bottom panel of the freezer, to access.

The panel may be held in place by retainer clips or screws. Remove the screws or depress the retainer clips with a small screwdriver. On some older top freezers it is necessary to remove the plastic molding to access the freezer floor. Removal of that molding can be tricky, so try not to force it, if possible. If you decide to remove it, you do so at your own risk. it will break, if forced. Warm it first with a warm towel, or hair dryer, set to low heat.

There are three primary types of defrost heater elements; exposed metal rod, metal rod covered with aluminum tape or a wire coil inside a glass tube. All three elements are tested in the same way.

The heater is connected by two wires. The wires are connected with slip on connectors. Firmly pull the connectors off of the terminals (do not pull on the wire). You may need to use a pair of needle-nose pliers to remove the connectors. Inspect the connectors and the terminals for corrosion. If the connectors are corroded they should be replaced.

Test the heating element for continuity using a multimeter. Set the multimeter to the ohms setting X1. Place a probe on each terminal. The multimeter should display a reading somewhere between zero and infinity. Because of the number of different elements we cannot tell what your reading should be, but we can be certain of what it shouldn't be. If the reading is zero or infinity the heating element is definitely faulty, and should be replaced.

freezer not defrosting. probably adaptive defrost board in fridge.
take panel off freezer (inside, back panel). if all frozen, can defrost with blow dryer. best to remove fridge control panel (inside, top of fidge). access adaptive defrost board, jump test to f1 (i think) next to test. this should initialize defrost mode. buy new board.

WARNING-It is a condition for the reader to take full responsability in attempting repairs and author shall not be responsible or liable for any damages. If you have no knowledge or experience to do this repair do not attempt it.

I have had the same issue with Fisher Paykel Active Smart fridge . This can be due to:
1) 12Volt fan in freezer is not functioning.
To test: open freezer door, place a magnet on magnet switch at the bottom of freezer where door seals(white plastic rectangle) It takes few seconds for fan to rev up so move magnet slowly until switch on. You can also close door and listen carefully if fan starts if unsure.
If fan works go to 2) 3)as defrosting resistance can be the trouble

2)If fan does not work . UNPLUG FRIDGE at the main plug
Empty freezer and defrost it if too icy (do not use sharp objects). Then on back panel you will see two holes on top. Put two hook tool and pull down and slightly forward until top lip is free. This is hard to do but the plastic panel is very strong so you can apply a bit of force there!!!
On the second panel is the fan, check wires are not broken (common cause of failure). unplug fan, you can check fan on 12V battery (+red). Buy a new fan if faulty and put freezer panel back.
3) If fan OK and you see a lot of ice on condenser (do not remove it by force, just let it melt completely) then the resistance is the cause of you trouble. It is delicate to remove and make sure FRIDGE IS UNPLUGGED! Do not force anything as condenser is very fragile and if you damaged it, your fridge can go straight to the dump. You can test the resistance with an Ohm meter to make sure internal resistance is broken or not. If broken replace it and your fridge will be fixed. If not broken then trouble is either with on board computer (very seldom) or the thermistance.