there are many other things to check first b4 assuming its ur defrost timer
FREEZER /FRIDGE NOT COOLING: Optimum refrigerator temperature at or below40° F(4° C). The freezer temperature should be0° F(-18° C). Check temperatures periodically. Appliance thermometers are the best way of knowing these
Check ur cold control thermostat, ur thermistors in both fridge and freezer ( they should be checked for both ohms and for amount of current being put out as per ur model ), ur air flow vent from freezer to fridge.( to make sure it opens and closes without any restrictions) On thermistors check for A close circuit and amount of ohms not just an Ohm reading. As per ur model. Most should atleast show 1200 ohms. Also Check door seals for leakage.
Poor cooling is often the result of a heavy frost build-up on the evaporator coils. You can't see these coils without removing a panel on the inside of your freezer. A sure sign that there is a build-up is the presence of any frost or ice build-up on the inside walls, floor, or ceiling of the freezer. Such a frost build-up usually indicates a problem in the self-defrosting system or damaged door gaskets.
If one of the components in the self-defrosting system fails, the refrigerator continues to try to cool. Eventually, though, so much frost builds up on the evaporator coils that the circulating fan can't draw air over the coils. There may still be a small amount of cooling because the coils are icy, but with no air flow over the coils, cooling in the refrigerator compartment is quite limited.
FAN check to see if it is operating or restricted A fan that is not blowing or restricted will not circulate the cold air properly.
Often, the first thing that folks do when their refrigerator starts to feel warm is turn both controls on the coldest settings.This is exactly the WRONG thing to do.Turning the cold control to the coldest settingwillkeep the compressor running longer and make lots of cold air.
But turning the air door to the coldest settingclosesthe airway to the food section. Lots of cold air is made, but most of it stays in the freezer section, and the food section actually getswarmer.
Self-defrosting refrigerators all have a set of coils and a cooling fan, usually under the refrigerator, that need to be cleaned regularly. If these coils get coated with dust, dirt or lint, the refrigerator may not cool properly. The coils may appear to be a thin, black, wide radiator-like device behind the lower kick-panel. To clean them, disconnect the refrigerator from the power source, use a refrigerator condenser brush and your vacuum cleaner to clean the coils of any lint, pet hair, etc. You may not be able to get to all of the condenser from the front, it may be necessary to clean the remainder of the condenser from the rear of the refrigerator.
May also need to check the defrost timer, u can get by and test manually by placing a small screw driver into the tiny slot or hole underneath the timer and turn slowly clockwise till u hear 1 click. this will engage ur defrost cycle in about 15 minutes u should be able to come back and feel the heat in freezer as it melts the ice providing ur terminator is not bad?
Another way to test it is with a multi meter. Remove timer it from fridge and you will see 4 prongs numbered 2,1,4,3 in that order. Place ur meter prong on prong 1 & 3 (if your fridge has a capacitor wired in series with the windings, then u check for micro fares rather than OHMS) If u cannot confirm this test, still try the next.
Take ur meter prong and connect to prong 1 & 4, it should read resistance or ohms ( closed) now remove prongs and place on prong 1 & 2, this should now read infinity or open (no ohms) now take a small screwdriver place it in the tiny hole or slot under the timer. Turn it clockwise slowly till u hear 1 click. Now ur 1& 2 should read closed ( showing ohms or resistance) now place meter prongs on 1 & 4 and you it should now show open ( or no resistance - no ohms) this is how u know ur timer is good, Remember when testing for ohms ADJUST meter to use a high ohms rating in the thousands as the resistance is very high in OHMS. And adjusting to low ohms rating may give a false reading or not show the proper resistance..
If you hear a clicking sound coming from the back of your refrigerator/freezer, then the problem is most likely the compressor, relay and or capacitor is overheating or not getting proper power and will not start.The compressor is the component on your refrigerator that allows your refrigerator to cool. If this component is not working properly your refrigerator will stop cooling. Most of the time the compressor is not the component that has failed.
To check ur compressor with multi meter:
Disconnect and remove the relay and capacitor from compressor, somes located next to compressor in a casing.
You wills see 3 prongs coming out of compressor. 1 goes to ur srtart winding, 1 goes to ur run winding and the center goes to ur ground.
Place ur meter connector or prong on the start prong and the other on the ground (center prong) take note of the reading in OHMS for example 5 ohms.
Next place meter prong on run prong and the center ground prong agin. Take note of the reading in OHMS. Example 4 ohms
Next place meter prong on the start prong and the other on the run prong, now take note of the reading example 9 ohms. Now match the total of this ohms test with the total of ur two separate test. 9 ohms, if they match ur ok give or take 5 percent plus or minus. One more test to make to test of there is a short in compressor attach meter prong to ground prong and rub the other end of meter prong to metal ( scrape the metal clean of paint and test on metal surface not painted surface. If it shows continuity or ohms , u have a short in ur compressor. It should show infinity
Lastly you should also check ur THERMISTORS in the freezer and fridge section for continuity OHMS and for amount of OHMS current being put out. In most models around 13000 ( give or take 150 ohms) ohms is required.