Refrigerator Defrost System

What you probably didn't notice was that the freezer has not been going through it's normal defrost cycle.   Because of this un-noticed event going on, there has been frost building up on the evaporator coils that doesn't belong there.   After this frost continues to build up over the course of a few days to a week or so, now you are going to start to notice the effects.

Here is what's happening when you have a malfunction in the defrost system.

• Air cannot circulate from the freezer(where the cold happens basically) to the fresh food section.
• Your refrigerator will run constantly to try to cool the fresh food section.   This will develop a new set of problems with your refrigerator.  More on that later....
• Excess frost builds up within the coils inside the freezer.  This is what is blocking the air flow to the fresh food section
• Usually you will notice the icemaker will stop making ice.  Poor air flow and not quite cold enough temperatures in the freezer cause this
• Water will not come through the dispenser on the door.   Cold air settles,  the water resovoir will freeze.
• Compressor may overheat and shut off.   This is when you hear, click, click, click.   Not good
• Ice Cream in the Freezer will start to get soft.  That's really not that bad.  lol

Defrost control or timer.

Some refrigerators have a defrost timer.  This type works like a clock.  Every eight hours or so the machine hits the defrost spot and that's when defrost occurs

Some refrigerators have an Adaptive Defrost Control.  This is what makes a refrigerator energy efficient.   It varys the length of time it takes the machine to go into defrost.   So instead of the energy hogging heater coming on every eight hours, it may be 24 hours, 18 hours, 10.5 hours, who knows.    It depends on how many times you have opened the doors, how long the compressor has run.   This is good because the refrigerator may not need to go into defrost every eight hours.   Now you are saving energy.  Good Stuff Top

Defrost Thermostat

This is the component that controls how long the heater stays on when the machine is in defrost mode.  Say the defrost cycle is thirty minutes,  the heater may only be on for ten of those thirty minutes on the timer controls.    On Adaptive Defrost Controls, when the heater shuts off, shortly after the machine exits defrost mode.   Basically if the heater only stays on for ten minutes, the whole defrost cycle will only be about 12 or 13 minutes long. Top

Basically when the heater comes on, it starts to melt the frost on the evaporator.  Once all the ice and frost is gone, the temperature behind the panel will start to rise.   Once the temperature behind the panel rises to a certain temperature, the thermostat will break the current of electricity going to the heater.   Bam, it shuts off and prevents your freezer from becoming a sauna, or an oven.   I'm sure you get the drift.     The heater is on the bottom of the evaporator coils and the defrost thermostat sits on top of the evaporator coils.

Defrost Heater

This is the last component in the defrost system.   This one should be pretty simple.  By now if you have read this far you should already know what this does and how important is it.   Some defrost heaters are a coil of wire in a glass tube under the evaporator coils.  Works like a light bulb basically.   The other style looks like the bake element in your stove.   They both get red hot either way and melt the frost.

So what happens now?   Well the first thing you can do to get the machine running is to remove the rear panel of the freezer.   From there you will want to remove all the frost and ice that has built up.   Pouring hot water over the coils is the best method.   The water will drain out of the freezer through the drain hole in the bottom of the freezer under the evaporator coils. Top