Fridge Freezer Repair Guide
Fridge Freezer Repair Guide Part 1; The Basics.
It firstly has to be said that no one without proper licensing and experience should attempt any electrical repairs, to do so may be illegal and very dangerous. With that out of the way, lets get started.
The vapor compression refrigeration or ‘reefer’ cycle hasn’t changed in the last 80 years, a gas is compressed, cooled, released, and re compressed, over and over again.
What has changed is the control and maintenance of that system.
Refrigeration technology has changed in the last 25 years to be far more sophisticated, fans, elements, switches, digital control, just to name a few.
So with the myriad of new improvements, a new technology every few months, how does one decipher the ultimate question, whats wrong with my fridge?
We will work through this on a step by step basis on a modern and vintage fridge freezer combo, as this is the most common style, starting with the symptoms.
FRIDGE NOT COOLING, FREEZER NOT COOLING.
This is really the most troublesome problem, as at first glance the refrigerator can seem like a total loss. Fortunately, this is also the easiest to diagnose by following these simple steps.
1. Is the power point working/ is it plugged in?
You wouldn’t believe how often this happens, remember if the safety switch or circuit breaker for the house is thrown and won’t re make while the fridge is plugged in, don’t try and fix this by yourself unless properly qualified and have access to an insulation resistance tester.
However if the safety switch is thrown, the usual culprit is a failed defrost element, and less likely failed compressor or fan.
2. Do the internal lights, or display work, yet no cooling anywhere?
If the lights are on but nobody’s home, the chances are good that the control system has failed, there are 2 major components to this, the main PCB for a modern fridge, or thermostat/ defrost timer in older fridges.
For older fridges, locate the defrost timer, inside the fridge section at the top (usually the cam can be seen through a small orifice with a screw on either side) or at the bottom, rear of the fridge, simply rotate the cam with a screw driver, if the timer is at fault you will here an audible click followed by the compressor coming on.
If the timer isn’t at fault, locate the fridge control knob and give it a few quick firm twists, this should free up a sticky thermostat. If still nothing after this, its time to start testing with a multimeter, the thermostat should be closed circuit.
For modern fridges with a bad board, unfortunately, replacement is the only option.
3. I can hear a fan running but blowing room temperature/ warm air?
If a fan is running, then the control system should be intact and therefore the issue will be with the sealed system, ie, compressor, or gas.
If the compressor is stone cold, then it is likely the compressor run relay has failed outright, the compressor is open circuit, or the main computer has failed to start the compressor.
Run relays are cheap to replace, main computers are moderately priced, a failed compressor is exceedingly expensive to replace and most will not attempt it.
If the compressor is red hot, then the fault will likely be a gas leak, Due to the EPA refrigerant handling laws, it is very difficult to replace a compressor if it has failed due to a gas leak, which is the root cause most of the time, making compressor replacement near impossible.
FREEZER COOLING BUT FRIDGE NOT COOLING
This is the most common complaint when it comes to refrigeration faults, depending on age, manufacturer and design, there could be up to a dozen reasons the unit is not cooling only in the fridge section, Below are the most common.
1. There is no air coming out of the vents in the fridge?
This is nice and easy, no flow, no chill. The most common mistake when feeling for airflow is forgetting to depress the light switch inside the fridge, if not visible, it may have a reed switch requiring the user to use a magnet to trigger the switch.
The Light switch (actually called a fan light switch) on many models, stops the fan from operating, this is called anti air spill, and prevents the fan from blowing chilled air out of the cabinet. Depress the fan light switch and feel for air flow, if the light stays on when depressed, the switch has failed.
If the light goes out but no air flow is felt at the vents, the chances are the vent damper which controls the volume of air directed into the fridge, has failed or is jammed, usually with ice.
In this case i recommend a 24 hour defrost, before replacing parts or seeking help. Most older fridges may have a failed fan motor, the freezer panel insulation was generally non existent in older fridges allowing the freezer to perform close to normal.
2. I can hear the fan motor running, but the airflow is poor.
This fault is a little more rare, and is generally the result of a failed defrost system which has allowed the evaporator core to plug with ice, negating airflow.
To diagnose this, the freezer panel will need to be removed to inspect the core, if full of ice, defrost and test the defrost system with a multimeter. Another possibility is a broken or dislodged fan blade, inspect it for position and condition, replace as necessary.
3. The fridge is between 10-18 degrees Celsius, but the airflow from the vent is great?
This is a good one, because its so counter intuitive, good airflow should mean good cooling right? wrong.
When the doors are closed, the unit is a sealed environment requiring a delicate balance of air pressures, air from the freezer is directed into the fridge which is circulated through the goods, then drawn back to the freezer to be chilled again and the cycle starts over.
What usually happens is the return from the fridge to the freezer (not user accessible in most cases) freezes over or becomes otherwise blocked. The only reliable remedy is to shut the unit down for 24 hours to clear the blockage.
If cooling performance restores however falls away again a few days later, you may well have a defrost system failure.
THE FREEZER ISN’T FREEZING BUT THE FRIDGE IS COOLING
This is the big one and depending on manufacturer, age and design could be attributed to the following in order of likelihood, defrost system failure, freezer fan failure (in twin fan models), micro gas leak causing a loss in performance, damper control fault, main computer or thermostat fault, a simple blocked defrost drain.
EVERYTHING IS GOING HAYWIRE
fridge is warm then cold, freezer defrosts and freezes again, frost everywhere? Have a big think, have you or someone else in the home left the fridge or freezer doors open? because that will wreak havoc on even the best fridges as it struggles to clear the humidity from both compartments while maintaining a set temperature.
If there is a chance the unit has been left open, shut it down for 24 hours and start again.
FRIDGE TEMPERATURE CONTROLS EXPLAINED
Ever wanted your fridge colder, so you turn the temperature down only to find it does nothing or gets warmer? here’s why.
99% of fridges control their temperature by cycling the compressor on and off in relation to the freezer temperature, and cycles the fan on and off in relation to the fridge temperature. When you turn the fridge dial to colder, it actually makes the compressor run longer, so you end up with a colder freezer and a colder fridge, here’s the problem, if the freezer dial is set to colder, the air guide to the fridge will be partially blocked by a valve behind that dial, negating any meaningful change to the fridge temperature.
So how do you make the fridge colder? leave the fridge dial at normal, and turn the freezer dial to warmer, that will deliver more air to the fridge section.
Want your freezer colder? turn the fridge dial to more cool, only move the freezer dial to more cool if you need to chill items rapidly as this will negatively affect the fridge section.
On modern digitally controlled fridges, depending on design, the system works much the same, altering the fridge temperature simply changes the vent damper open duration and angle.
On very modern fridges, an electronic valve controls the refrigerant gas flow, this is a highly efficient design, yet wholly unreliable over the long run and very difficult to diagnose.
HOT FRIDGE WALLS
Australia is Hot, and in summer, fridges not suited to our climate struggle to do away with the heat they generate. To combat this, fridges are designed with 2 different systems, small fridges with less than 400 or so litres capacity generally use the walls of the fridge as heat sinks and release the heat by radiation (also called natural draught cooling).
Larger fridges which handle higher loads are normally equipped with a fan assisted pre-cooler located next to the compressor, the fan passes air over the bundle of pipes, called a condenser, which gives up most of its heat by convection, the walls of the fridge do the rest.
So when the walls of your fridge are hot, if its small, its just a hot day, turn on the A/C and lower the homes temperature.
If its a big fridge and the panels get to hot to handle, the usual culprit is a failed condenser fan, in which case to save the compressor from cooking itself, shut the unit off until a repair can be made.
Now that your armed with the basics of domestic refrigeration diagnostics, when you want to tackle a repair, or need to call a professional, you’ll be able to get a head start, making an over the phone diagnostic or estimate that much easier and more importantly, clear and precise.
As always, Knowledge is power.