What causes the coils behind the panel in the freezer to freeze up and stop the freezer fan? top half of freezer defrosts, lower half stays cold.Fridge is side by side and freezer fan keeps turning of

compressor wont shut off till temp reached in unit it will take awhile because you have defrosted and it takes time for freezer to reach temp

It should shut off after satisfying the thermostat control setting. The control could be bad or the refrigerator is not cooling enough. Check to see if the coils under the refrigerator are not blocked with lint and the fan by the compressor in back is turning. Also check if the fan blade is not dirty with lint. These things could cause the refrigerator to run constantly.

the evaporator fan is not spinning. the coil is getting too cold because the fan is not circulating the air across it. defrost it and see if the fan works. If not, they are fairly inexpensive and easy to replace. There is an access cover on the back wall of the freezer. remove it, and the fan is right behind it.

This sounds like an air flow issue, If your freezer fan is running still you may have a defrost problem starting in the freezer cooling coils. This will cause the cold from the freezer to back flow into the bottom of the fridge and only the lower half of the freezer to keep very cold.
Most likely culprit for defrost issues would be the terminating thermostat (inside freezer behind back wall and clips to top of coils).
Good luck and let me know if you need more help!

There is a fan behind the back wall of the freezer about 1/2 way up from the bottom, you should be able to hear this running when the freezer is on. If you do not hear this then you need a new evaporator fan motor.

If you hear the fan run then you most likely have a problem with the automatic defrost cycle that would most likely be the heat element that is located just below the coils inside the freezer behind the panel.

The fridge gets its cold air from the freezer through a vent(damper) between the freezer and fridge.The fan in the freezer blows air through it. Make sure this fan is running. You may have to hold the door switch in for it to run. There is a flap you adjust with the fridge temp. control. Make sure it's opening and closing when you adjust the fridge temp.
The problem could be the electronic control if you have one or the mechanical linkages.

If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air and eventually affect the freezer too.

check defrost timer, defrost heater, defrost thermostat. In most newer models the timer has been replaced by an electronic control board. If the heater and thermostat are ok it’ll be the control.

Good day,
35 minutes would be considered nominal. That is the amount of time needed to heat up the cooling coils behind the rear panel in the freezer compartment, and then allow it to drain the condensate water out the drain.

The defrost cycle is made up of 2 parts.
The first part involves shutting all fans and compressor off, and turning on the heater/heaters mounted on the bottom of the cooling coil to above freezing. About 10 to 15 minutes.

The second half occures when a defrost thermostat mounted on the top of that coil senses the coil is above freezing. It cuts the power to the heaters, and lets the system just idle, while the water is allowed to drain out of the drain.

If that tstat is working properly, the food temperature is affected slightly but never to an above freezing condition.
The thermostat is a small 1" round disk clipped to the top of the coil.

Only one possibility, but that tstat could be hanging allowing the freezer coil compartment to reach a very high temperature. If so, it needs replaced.

You should also check to see if both fans and compressor start running as soon as the cycle is done.

Dirty coils not likely the problem .
Open the freezer door .( Behind the back panel ( inside the freezer ) is the evaporator fan motor . ) Push in on the freezer door switch , and listen for the fan to come on . Sometimes , the fan will stay on , even if the door is open . Do you hear the fan ? If not , then the main control board , behind the refrig , behind an 8 " X 10 " panel , is probably bad . If you do hear the fan , then you are having a defrost problem . Pull the refrig out and remove the 8 " x 10 " panel .
Behind this panel , is the main control board . Unplug the refrig . Remove the BLUE plug from the board , with 3 larger wires going to it . Looking at the blue plug , the sequence will be wire1,wire2,space,wire3 . Get a short piece of insulated wire , and strip about 1/4 inch from each end . Insert 1 end into wire2 , and the other into wire3 . Plug the refrig back in . After about 3 min , look in the freezer , at the bottom , behind the crisper , look for a red glow . If no red glow , unplug the refrig , and reassemble the plug and cover . This no glow , indicates a shorted defrost heater WR51X10101 . It is also advisable to replace the defrost thermostat ( pt. number WR50X10068 ) when replacing the heater . To access these parts , you will have to remove the inside rear wall of the freezer . The heater , is at the bottom of the coils , held on with 2 screws , and the thermostat , is the 1 " cylinder , with a blue and pink wire going to it , clipped on the top left of the coils .
If you do get a red glow , then the # 4 thermistor is bad . This tells the main control board , the temp of the coils , if they need defrosted , when they are thru defrosting . This thermistor is the 1 " long , torpedo looking piece , clipped on the top left of the coils , with 2 white wires going to it . Part number WR55X10025 . It would be advisable to also replace the # 5 thermistor , located at the bottom of the freezer , slightly in front of the drain , also with 2 white wires going to it , slid into a housing . This thermistor , is the freezer thermistor , which tells the control board , the freezer temp , and , when to cycle off , due to set temperature reached .

It sounds like the evaporator fan is hitting ice that is built up on the evaporator coil. When it's making the noise, open the freezer door and see if it stops.
(Most models are wired so that the evaporator fan cuts off when the freezer door is open.)
Check the inside back, lower panel of the freezer for ice built up or frost on it. If there is, you have a defrost problem that is most likley a bad heater. It's located around the coil inside the freezer behind the panel you will be looking at. The defrost problem would explain the freezer not freezing ice cream.

warm between doors is normal. if hot then clean coils and if coils clean make sure condenser fan motor working thats the fan in the back compartment, however if warm thats good. did the evaporator coil freeze from top to btm is that why u replaced heater. if it was then could be heater,if the coil is only getting frost on half the coil,you could have a sealed system problem. is the evaporator motor working in the frz side if not,then that could be the problem.if coil is froze up it needs to be defrosted. did you defrost coil when you replaced heater,if not try defrosting coils and then wait about 12 hrs and see how it does.