Freezer is not defrosting - Whirlpool Refrigerators

Can you remove the rear panel in the back of your freezer and tell me what the frost pattern looks like? When a refrigerator loses Freon the frost pattern looks like this photo HERE If the rear wall of your freezer looks like this you still are having a defrost problem photo HERE
Here is what that will look like behind the rear panel of the freezer should the defrost heater and defrost thermostat need replaced HERE
You mentioned that you have already replaced the defrost timer so we should not be concerned about that. The defrost heater=> 2315530 Defrost Heater

The defrost thermostat=> 4387503 Defrost Thermostat

I will be here should you have questions or comments, Thanks Sea Breeze

I am pretty sure the model number you are referring to are HSS25IFMCC / HSS25IFMWW This model has no defrost timer like the typical defrost timer. The defrost time is determined by the Motherboard. If you are having defrost problems with your model it is most likely the defrost heater causing the problems. The defrost heater is part=> WR51X10055 Defrost Heater

Most times after manually defrosting the defrost heater on your model can be seen burned out
by just looking at the outer glass of the heater itself. This takes unplugging the refrigerator and removal of the rear panel inside and back wall of the freezer

Most times after manually defrosting the defrost heater on your model can be seen burned out Testing the defrost heater can be found here=> WR51X10055 Defrost Heater Assembly Once inside the freezer it is always a good idea to change the defrost thermostat, Click Here=> WR50X10054 Defrost Heater
I will be here should you have questions, Thanks Sea Breeze
Click Here=> HSS25IFMAWW Freezer Components parts 230 is the Defrost Heater and part 230 is the Defrost Thermostat

The freezer is not defrosting. Look at the back wall of the freezer section and see if it is frosted. Locate the defrost timer and advance it till it clicks once. This should advance the freezer to the defrost cycle. Check to see if the defrost heater is on. If the defrost heater is glowing behind the freezer rear panel the you know you have to replace the defrost timer. If the heater is not glowing then you have to check if the defrost heater or defrost timer is in default.

Model number is always valuable in order to be able to give you more accurate information.

Check rear wall of freezer by feel for frost. Heavy, even frost indicates likely problem in the defrost system. Defrost heater (most likely and in freezer behind rear wall), defrost thermostat (in freezer-must be checked at freezer temperature) or one of Defrost timer or Defrost control (Circuit board) generally located in Refrigerator compartment but may be inside rear of outer case. Defrost heater and defrost thermosts can be checked with an ohmmeter. Disconnect power to refrigerator, remove rear wall and disconnect at least one side of any component you are testing. If the heater and defrost thermostat test good for continuity then replace the defrost control.

Without repair refrigerator will work perfectly for about 7-10 days after being COMPLETELY defrosted, including behind freezer panel, until thick frost builds up again cutting off air flow to both compartments

Check rear wall of freezer by feel for frost. Heavy, even frost indicates likely problem in the defrost system. Unplug unit. Defrost heater (in freezer behind rear wall panel), defrost thermostat (same area-must be checked at freezer temperature) or Defrost timer-located lower back outside of unit. Near compressor. Do continuity test on heater and defrost thermostat and if they show continuity (good), replace defrost timer. If not, replace the one that tests bad.

Defrost coils fully. Reassemble.

Please let me know if I have helped with comments and rating.

Refrigerator will work about 7-10 days after being defrosted until thick frost builds up again cutting off air flow to both compartments

That snow is the condensate build up on the evaporator coils behind the rear panel of your freezer. Normally the freezer will go into defrost about every 10 hours and this snow will melt and drain out the defrost condensate line below the evaporator and go to a pan under your refrigerator and return back to the air inside your home. I believe your freezer is missing the defrost cycle either because the controls for the defrost are defective or the defrost heater and defrost thermostat is defective. I would be watching for an increase in refrigerator temperatures soon, due to loss of defrost. We will need to unplug and examine the evaporator coils behind the rear wall of the freezer. If frozen or covered with snow then defrost with a hair dryer and lets check the defrost heater and all its related components. Sea Breeze

Repair the defrost system, defrost timer,defrost thermostat and defrost heater.

If freezer is icing up, 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

If the freezer is in defrost then the freezer fan should be off. Only on the electronic will the freezer fan come on in defrost but the freezer door has to be held open for 3 min before the fan comes on

ok,is the freezer fan working?is there frost buildup in the freezer?it sound like you have a defrost problem whick means your defrost timer,defrost heater or defrost sensor has failed,you need to check all the defrost parts to pin point the problem,let me know what you find-mike