Maintaining and Troubleshooting Domestic Refrigerators: Chapter 2
Refrigerator Troubleshooting: Primary Components Part 1
In this module, we will discuss the common refrigerator problems associated with primary components. We will also learn how to fix these problems. Skip to quiz!
Diagnosing malfunctions
Refrigerators can last for many years without any major faults or damages if we perform periodic maintenance. However, if proper care is not taken, they can start showing signs of trouble and may need repairs.
Some of the common signs of trouble are:
The refrigerator is making unusual noises
Items inside the refrigerator don’t remain as cool as they used to
Water in the fridge
Water under the fridge
Refrigerator lights not working
Fridge not defrosting
Water dispenser not working
Ice maker is overflowing
The temperature in the freezer section is higher than normal
There are underlying causes for the signs of the trouble of the refrigerator. These causes are due to faults in the individual system such as:
Primary and secondary components,
Dispenser system,
Defrost system,
Electrical system, and
Control system
Some refrigerator models have diagnostic test modes in them to detect the cause of the problem. The test mode allows us to diagnose the malfunction inside the refrigerator. However, the method of activating diagnostic test mode varies from model to model.
The method of activating diagnostic test mode varies from model to model. We can find the information to enter the test mode in the tech sheet provided by the manufacturer. The sheet is usually located behind the bottom front grill or taped to the back of the refrigerator.
The refrigerator runs through several tests to diagnose a problem. We will need to unplug our refrigerator from the power outlet for at least 30 seconds to exit the test mode. Once we plug it back in, our refrigerator will have exited diagnostic mode.
Since we use the refrigerator every day, we need to get it repaired or serviced as soon as any problem is detected.
The primary components of the refrigerator that may get malfunctioned and need troubleshooting are:
Compressor,
Condenser, and
Thermostat
Let us discuss signs of trouble that occur due to these components and how to troubleshoot them.
Compressor
The typical complaints associated with failure of the compressor are:
The refrigerator temperature is warm.
The freezer temperature is warm.
The refrigerator does not run at all.
Food is spoiling.
The compressor may fail to run because of:
No power supply
Faulty start relay
Faulty thermistor
The electronic control board has gone bad
Possible broken wires
If the fridge is not cooling, the compressor doesn't get power. We need to first check for the power button. Make sure the refrigerator light is on. This will ensure that compressor is getting power.
Recall that the control board sends a control signal to the fan relay by default when the compressor starts. The fan relay then starts the fan motor. So, another way to ensure that compressor is getting power is by checking the condenser fan or evaporator fan.
If the condenser or evaporator fan runs, the compressor is also getting power. This is because the compressor shares a circuit with the condenser and evaporator fan motor on most refrigerators.
How to Inspect Relays
Recall that the relay supplies electricity to a secondary winding of the compressor motor to give it extra starting torque. If the relay is faulty, then the compressor won't run. Next, we should check the start relay.
The troubleshooting for relay differs according to the type of relay used. The types of relay we usually find on the refrigerator are:
Separate relay, and
Combination relay
Recall that overload protects the motor from overheating and winding damage. The separate relay type has a separate overload protector, whereas the combination has a built-in overload on the bottom side of the relay.
To troubleshoot these relays, we use three methods:
Rattle test,
Continuity test using a multimeter, and
Resistance test using a multimeter
Let us take a look at each of them.
Before starting troubleshooting of relay, we need to remove it from the refrigerator. Recall that it is located at the backside of the refrigerator. For safety, unplug the refrigerator. Unhook the retainer clip and pull the start relay out of the refrigerator.
For the rattle test, we need to shake the start relay. Depending on the output sound, we can decide the relay is good or bad.
The overload will always have a slight rattle to it. Since the combination relays always have an overload built into them, they constantly rattle. The separate relay used in the older refrigerator always rattle, whereas the other one does not rattle if it works fine.
If the rattle test does not give the correct result, check for continuity. Recall that the perpendicular terminal will be the “outlet” of the relay, and the center of the remaining three terminals will be the “inlet.” The other two are the control pins.
For measuring continuity, we need to connect multimeter leads into control pins of the relay.
If the multimeter beeps, the relay is good.
If the relay is faulty, the multimeter will read 0L or 1 in the far left digit. If the start relay is working correctly, we may have a defective compressor.
We can also perform a resistance test by setting the multimeter to the Ω setting. The multimeter should give close to 5Ω resistance for a good relay. If the relay is bad, the multimeter will give no reading or very high resistance reading.
Other Causes of Compressor Malfunction
The compressor may also not work if we have a defective:
Electronic control board, and
Temperature sensor.
We can run the diagnostic test mode to ensure our compressor is running fine before diagnosing these components.
Recall that the control board receives input from temperature sensors to operate the compressor. A bad thermistor does not send a signal to the control board. This prevents the compressor from running in normal operating mode.
The diagnostic test mode forces the compressor to run whether the thermistor is broken or not.
If the compressor starts in the diagnostic test mode, we need to replace the thermistor.
If the compressor doesn't run in the diagnostic test mode, the thermistor is working fine. The only possible cause of compressor malfunction is a break in the control board wiring or a bad control board. We can then check continuity from the electronic control board through the compressor circuit.
If the compressor circuit is open, we will get an OL or 1 in the far left digit on the multimeter.
This means the compressor is not getting power.
We need to then look for pinched or broken wires in the control board harness and on the wires leading up to the compressor. We should repair or replace all the broken wires in the circuit. If no broken wires are present, we should check continuity from the control board to the compressor.
A reading of about 5 ohms indicates continuity in the compressor circuit. If we get the continuity in the circuit, then the cause of the compressor not getting power is a faulty electronic control board. This is because the board isn’t sending voltage through the circuit to the compressor.
The common problems in the refrigerator are due to a fault in the individual systems. Some refrigerator models have diagnostic test modes in them to detect the cause of the problem.
The primary components of the refrigerator that may get malfunctioned and need troubleshooting are:
Compressor,
Condenser, and
Thermostat
We will go over the condenser and thermostat troubleshooting in the next topic.
Refrigerator Troubleshooting: Primary Components Part 2
In this module, we will discuss the common refrigerator problems associated with primary components. We will also learn how to fix these problems. Skip to quiz!
Condenser
The complaints associated with bad condenser coil are:
Overheating of the compressor, and
The refrigerator is too warm
Recall that the dirt on the condenser coil acts as an insulator and does not allow the heat to dissipate. This causes improper cooling of the refrigerant. This leads to improper cooling of the refrigerator.
Dirty condenser coils cause the compressor to overheat. Overheating causes the compressor to stop working, and the entire refrigeration process stops as well. We need to dust the coils to troubleshoot these issues.
Thermostat
Recall that the ideal temperature in the refrigerator for keeping food and drinks cold is between 32℉ to 40℉. The thermostat plays a vital role in maintaining this temperature inside your refrigerator. If we suddenly notice that food isn’t as cool as expected, then a faulty thermostat can be a reason.
The common signs that indicate our fridge is suffering from a faulty thermostat are:
The fridge is not cool enough,
The fridge is getting unusually cold, and
Fluctuation in the fridge inside temperature
If the fridge is not cool enough, the food can get spoilt. The food can get frozen if the fridge is getting unusually cold. To avoid these problems, we need to troubleshoot the thermostat.
For troubleshooting the thermostat, unplug the refrigerator. Next, locate the thermostat dial. The thermostat is located directly behind the dial.
Then, we should remove the plastic cover that protects the thermostat and its controls. Some covers are screwed into place, while others are held in place by plastic clips. Depending on our make and model refrigerator, we may have to remove the dial before taking the cover off.
Next, we should remove the two wires on the thermostat. Set the multimeter to continuity setting. Then, touch both the multimeter probes to one terminal on the thermostat. If the multimeter beeps, the thermostat is working fine.
Now we should check resistance across the two terminals of the thermostat. Set the multimeter to Ω setting. Then, touch one of the multimeter probes to one terminal on the thermostat and the other probe to the other terminal.
The multimeter will read 0L or 1 in the far left digit when the thermostat dial is OFF. Next, rotate the thermometer dial and check the resistance. The multimeter should display some resistance value when the thermometer is ON. Let us look at the video that shows this.
If the thermostat is not working correctly, we need to replace it.
The panel behind the thermostat knob is opened. Then all the wires and clips on the thermostat are removed. Before removing the wires taking a picture of a wired thermostat helps while installing a new one.
The complaints associated with bad condenser coil are:
Overheating of the compressor, and
The refrigerator is too warm
We need to dust the coils to troubleshoot these issues.
The common signs that indicate our fridge is suffering from a faulty thermostat are:
The fridge is not cool enough,
The fridge is getting unusually cold, and
Fluctuation in the fridge inside temperature
We check the continuity of the thermostat to troubleshoot it.
Refrigerator Troubleshooting: Secondary Components
In this module, we will discuss the common refrigerator problems associated with secondary components. We will also learn how to fix these problems. Skip to quiz!
Diagnosing malfunctions
The problems in the refrigerator can occur due to the malfunctioning of secondary components. These include:
Evaporator fan motor, and
Condenser fan motor
Let us go over each of them.
Evaporator Fan Motor
The common problems due to faulty evaporator fan are:
The refrigerator is not cooling
The evaporator fan motor is noisy
The evaporator fan motor does not run at all.
Recall that the evaporator fan blows air across the evaporator coils and through the refrigerator cabinet for cooling. If our refrigerator isn’t cooling well, the fan isn’t running or blowing cool air like usual.
The evaporator fan may fail to run because of:
The faulty electronic control board
Possible broken wires
Faulty fan motor
Let us discuss how to troubleshoot them.
First, test if the evaporator fan runs in the diagnostic test mode. Recall that the instructions for activating diagnostic test mode are available in the tech sheet provided by the manufacturer.
Recall that the control board senses the compressor needs to operate. Then it sends voltage to the compressor and fans to begin the cooling cycle. If the evaporator fan runs in test mode, it means the faulty control board is not sending voltage to the fan.
We need to replace the faulty control board.
To replace the control board remove the screw that holds the control box. Remove the control board wiring harness. Connect the wires to the new control board and mount the control box in place.
If the evaporator fan doesn't run in the diagnostic test mode, check for a break in the wiring. Remove the screw that holds the control box and lower the control box. Check the wire for visible damage. Repair the wire if it's pinched or broken.
If the wire isn’t visibly damaged, check for electrical continuity in the wires supplying power to the fan. Put a multimeter lead on the wire going to the fan and control board. If the wire is intact, the multimeter reads near 0 ohms. Check the light blue wire in the same way.
If both wires have continuity, the problem is with the fan motor or the electronic control board. If neither wire has continuity, then we should look for pinched or broken wires.
If there is no issue with the wiring and control board, we must check the evaporator fan motor. The evaporator fan motor has a control board inside the motor casing, so you can’t check for continuity. Instead, remove the support bracket and fan motor cover to examine the fan control board for damage.
We need to replace the evaporator fan motor if the board has visible burn marks. If you don’t see any damage, test the evaporator fan.
For testing the evaporator fan, put the multimeter on the Ω setting. Connect the multimeter lead to two wires of the evaporator fan. If the multimeter reads resistance in the range of 10 Ω to 100 Ω, the evaporator fan is working fine.
If the multimeter reads less than 10 Ω resistance, we should replace the evaporator fan motor.
We need to push the evaporator fan cover up and pull the fan blade off the motor shaft. Then, lift the motor out of the mounting bracket. We then insert the new fan motor in the mounting bracket.
Condenser Fan Motor
The complaints associated with the failure of the condenser fan motor are:
The refrigerator temperature is warm.
The condenser fan motor does not run at all.
Noisy fan motor
Much like an evaporator fan, the condenser fan may fail to run because of:
A faulty electronic control board
Possible broken wires
Faulty fan motor
We will have to troubleshoot these issues the same way.
If there is no problem with the control board and wiring, we need to replace the fan motor.
We need to pull the fridge away from the wall. Then, we should remove the thin panel on the back near the bottom to access the condenser fan.
Next, we should remove the wires connected to the old fan. Connect the new fan with wire connectors. Screw the new fan to the bracket and reinstall the fan and bracket in the fridge.
The evaporator fan and condenser fan may fail to run because of:
A faulty electronic control board
Possible broken wires
Faulty fan motor
We troubleshoot these components to keep the refrigerator cool.
Question #1: Which of the following is a common problem in the refrigerator? (Select all that apply)
Water under the fridge
Fridge not defrosting
Refrigerator burning food kept inside
The refrigerator is making unusual noises
Scroll down for the answer...
Answer: Water under the fridge
Fridge not defrosting
The refrigerator is making unusual noises
Some of the common problems in the refrigerator are:
The refrigerator is making unusual noises
Water in the fridge
Water under the fridge
Fridge not defrosting
Question #2: How does the refrigerator come out of the diagnostic test mode?
By turning off the ice maker power
By changing the temperature of the thermostat
By unplugging the refrigerator power
By opening the refrigerator door
Scroll down for the answer...
Answer: By unplugging the refrigerator power
We will need to unplug our refrigerator from the power outlet for at least 30 seconds to exit the test mode.
Question #3: What are the problems associated with a faulty compressor of the refrigerator? (select all that apply)
The refrigerator temperature is warm.
Fridge not defrosting
The refrigerator does not run at all.
Ice maker is overflowing
Scroll down for the answer...
Answer: The refrigerator temperature is warm.
The refrigerator does not run at all.
The typical complaints associated with failure of the compressor are:
The refrigerator temperature is warm.
The freezer temperature is warm.
The refrigerator does not run at all.
Question #4: Why does the refrigerator compressor fail to run? (select all that apply)
Faulty electronic control board
Faulty thermistor
Faulty defrost heater
Faulty start relay
Scroll down for the answer...
Answer: Faulty electronic control board
Faulty thermistor
Faulty start relay
The compressor may fail to run because of:
Faulty start relay
Faulty thermistor
Faulty electronic control board
Possible broken wires
Question #5: What are the methods to troubleshoot faulty compressor start relay? (select all that apply)
Rattle test
Nitrogen purging
Continuity test using a multimeter
Resistance test using a multimeter
Scroll down for the answer...
Answer: Rattle test
Continuity test using a multimeter
Resistance test using a multimeter
To troubleshoot relays, we use three methods:
Rattle test,
Continuity test using a multimeter, and
Resistance test using a multimeter
Question #6: What are the problems associated with a dusty condenser coil of the refrigerator? (select all that apply)
The refrigerator temperature is warm.
Fridge not defrosting
Overheating of the compressor
Ice maker is overflowing
Scroll down for the answer...
Answer: The refrigerator temperature is warm.
Overheating of the compressor
The typical complaints associated with bad condenser coil are:
Overheating of the compressor, and
The refrigerator is too warm
Question #7: What are the problems associated with a faulty thermostat of the refrigerator? (select all that apply)
The fridge is not cool enough
Fridge not defrosting
Fluctuation in the fridge inside temperature
Ice maker is overflowing
Scroll down for the answer...
Answer: The fridge is not cool enough
Fluctuation in the fridge inside temperature
The common problems because of a faulty thermostat are:
The fridge is not cool enough,
The fridge is getting unusually cold, and
Fluctuation in the fridge inside temperature
Question #8: How do we troubleshoot the refrigerator thermostat?
By rotating the thermostat knob twice
By checking resistance across the two terminals of the thermostat
Using rattle test
By calibrating with ice maker thermostat temperature
Scroll down for the answer...
Answer: By checking resistance across the two terminals of the thermostat
We should check resistance across the two terminals of the thermostat to troubleshoot it.
Question #9: Why does the refrigerator evaporator fan fail to run? (select all that apply)
Faulty electronic control board
Faulty thermistor
Faulty defrost heater
Faulty fan motor
Scroll down for the answer...
Answer: Faulty electronic control board
Faulty fan motor
The evaporator fan may fail to run because of:
The faulty electronic control board
Possible broken wires
Faulty fan motor
Question #10: If the wire is pinched or broken, there will be no electrical continuity in the circuit.
True
False
Scroll down for the answer...
Answer: True.
True. If the wire isn’t visibly damaged, or broken the circuit is not continuous. We need to check for the electrical continuity of such wire using a multimeter.
Question #11: Why does the refrigerator condenser fan fail to run? (select all that apply)
Faulty electronic control board
Faulty thermistor
Faulty defrost heater
Faulty fan motor
Scroll down for the answer...
Answer: Faulty electronic control board
Faulty fan motor
The condenser fan may fail to run because of:
The faulty electronic control board
Possible broken wires
Faulty fan motor