Refrigerators

Cooling in refrigerators is achieved with the help of an Evaporator Fan and a Condenser Fan.

The evaporator fan circulates the air between the freezer and food section of the refrigerator.

The condenser fan circulates air through the condenser coils and helps to keep the compressor cool. The condenser fan also dissipates heat absorbed by the condenser coils into the atmosphere that is required for proper cooling to occur.

Some Models of refrigerators have other fans that are used to independently adjust temperatures in other sections of the fridge, but all modern fridges have at least an Evaporator Fan and Condenser Fan.

Most refrigerators today contain at least 1 control board and a few other boards to control dispenser function, human input, and a host of other functions.

The control board is essentially the Brain of the refrigerator and collects sensory input from numerous sensors in the freezer/food section, the run time of the compressor, the amount of times the doors have been open, the Fans, and so forth.

Symptoms of a bad control board vary from cooling problems, erratic behavior, or the fridge not working at all.

These control boards are in effect the same type of computer boards that are used in everyday computers and therefore susceptible to power outages, surges, spikes, and even to static electricity.

If you’ve had a recent power outage and your refrigerator is not working properly, it could be because the control board is bad.

Control boards vary in price and can be expensive, so if you suspect a bad control board, its best to have a professional to do the diagnosis.

Modern refrigerators achieve cooling through the “Seal System”

The seal system consist of the Compressor, Condenser, Evaporator, the tubing that connects them, and Freon.

Seal System problems are normally fatal and very expensive to repair.

The compressor is like the “Heart” of the fridge, its a pump that circulates freon through the condenser and evaporator.

If your heart stops, you wont have much time to live. So if the compressor stops, the freon wont circulate, and the fridge will not cool whatsoever, even if the lights are on, the fans are blowing, and it seems like the fridge is running.

You basically need a heart transplant at this time which can be a very expensive and tedious repair. Depending on the age, make and model of your fridge, many times it is not worth repairing the fridge.

A good thing about compressors is that they have an electrical start/safety device that powers it on. This prevents the compressor from overloading, or starting when it shouldn’t. Occasionally the start/safety device will fail, and the compressor wont run, therefore seeming like its a bad compressor. Many times you can replace the start device at a relatively low cost. However, the compressor could be potentially damaged from when the start device goes out, or, even if you successfully replace the start device, there’s no telling how long the compressor or anything else will last.

Refrigerators don’t “make” cold, they remove heat particles from inside the Freezer and Refrigerator cabinet, and transfers the heat to the atmosphere through the Condenser. With help from the Condenser Fan Motor, heat that was extracted from the evaporator, and has been collected in the condenser, is dissipated into the atmosphere through heat exchange.This is why you need to keep the “Coils” under the fridge clean. If heat exchange can not occur, you will have loss of cooling in both Freezer and Food sections. If you notice a loss of cooling, check and clean the condenser if it is dirty and hasn’t been cleaned in awhile.

The Evaporator is located inside the Freezer, some models have a separate Evaporator in the Food section. Freon is pumped into the Evaporator by the compressor at very high pressures and boiling temperatures. The Freon explodes into the Evaporator and the high pressure and temperature causes the Freon to attract the heat particles inside the entire Fridge cabinet. The result is the seemingly “Cold” it makes. The Evaporator Fan Motor is normally located directly by the Evaporator and circulates the air between the Freezer and Food section. The bigger the Fridge, the longer this process takes, this is why you must allow 24 hours for changes to occur when you first start you fridge, or make changes to the temperature controls.

The seal system is a “sealed” system of different metals and tubing that need to be welded together to deal with extreme pressures and temperatures. Occasionally the tubing can develop small pin hole leaks, and the freon will leak out of the system. The freon is not meant to leak out, so the leak will need to be sealed properly, and Freon recharged.Sometimes the seal system will become restricted, normally from moisture that builds up in the tubing, and the Freon cant flow through the system.

Unless you have a real expensive Fridge, or a built in refrigerator that is big and expensive to replace, most seal system problems are not worth repair.

Defrost Problems

In order for the refrigerator to work properly it must defrost the freezer every few hours to prevent the evaporator from accumulating Ice build up and stopping the airflow between the freezer and food section of the refrigerator.

A defrost problem can either be caused by a bad defrost thermostat, defrost timer, bad control board, thermistor, or defective defrost heaters.

With the help of some type of computer board and sensor, Modern refrigerators defrost themselves as they see fit. When the refrigerator determines that it needs to defrost itself, it will start the defrost cycle for however long it needs to defrost the evaporator which is located in the freezer section. This is achieved with the help of sensors, thermostats, and a heating element. There will either be a metal rod heater, or a glass style heater that heats up when electricity runs through it.

Once the evaporator has sufficiently defrosted, a sensor or thermostat will send a signal to the control board that it is thoroughly defrosted and tell it to begin the cooling cycle again. When a defrost system has failed, whether it is the defrost thermostat, defrost timer, bad control board, thermistor, or defrost heater, the evaporator fan can not properly circulate the air between the freezer and the food section.

This will result in the food section to appear to be “not as cold as it used to be.”

You can expect a 5-20 degree loss of cooling in the food section, and in severe cases the freezer will begin to lose temperature, and food will begin to go bad.

A tell tale sign that you have a defrost problem is if you have excessive Ice build up on the back wall of the freezer. Most people don’t notice the ice build up because of food being in the way.

Although recognizing a defrost problem is relatively common, and the actual process of repairing the defrost system is pretty simple, it still can be challenging to diagnose, especially when dealing with a control board that performs many other functions of the refrigerator.

This is why it is important to have Don’s Appliances professionally diagnose your appliance.