Multimeter: Testing Refrigerator Parts
Test to see what refrigerator parts you might need!
You will need a multimeter to test!
An inexpensive one should work for a few simple tests.
An inexpensive one should work for a few simple tests.
*(See notes at the bottom of this page for more information on ohms, continuity, circuits)
The
Warm, it will be open (no continuity) and cold, it will be closed (continuity). You can test warm and cold as indicated above.
On this refrigerator, the heater element and defrost thermostat are sold as one unit, so if one is defective, the whole unit must be replaced. (Don't try to save a few cents by splicing.) Some defrost thermostats may be separate, requiring only that item to be replaced. But consider the cost, and decide whether to replace them both while you have the freezer cleared and opened.
defrost thermostat
can be tested by inserting the red probe in the white/pale green wire to the left. Black probe stays in the middle slot.Warm, it will be open (no continuity) and cold, it will be closed (continuity). You can test warm and cold as indicated above.
On this refrigerator, the heater element and defrost thermostat are sold as one unit, so if one is defective, the whole unit must be replaced. (Don't try to save a few cents by splicing.) Some defrost thermostats may be separate, requiring only that item to be replaced. But consider the cost, and decide whether to replace them both while you have the freezer cleared and opened.
A defective defrost thermostat can prevent the defrost heater from turning on or it could allow it to overheat. During a defrost cycle, the defrost heater causes the bi-metal alloy in the switch to warm. As it does, it opens the circuit. As the bi-metal cools, it makes the circuit close.
Using the multimeter, at room temperature the defrost thermostat should indicate an open circuit, i.e., shows no continuity. When cool, the defrost thermostat closes the circuit, i.e., continuity. This allows the defrost heater to heat, when the ADC or defrost timer completes the circuit when conditions indicate a defrost is needed.
You can test it when cool by using some ice in a plastic bag to make it “cool.” No ice? Use a can of gas duster (computer keyboard cleaner) turned upside down and spray the thermostat with a few shots to make it cold. (USE EYE protection, i.e., safety glasses and keep your fingers out of the way!)
Using the multimeter, at room temperature the defrost thermostat should indicate an open circuit, i.e., shows no continuity. When cool, the defrost thermostat closes the circuit, i.e., continuity. This allows the defrost heater to heat, when the ADC or defrost timer completes the circuit when conditions indicate a defrost is needed.
You can test it when cool by using some ice in a plastic bag to make it “cool.” No ice? Use a can of gas duster (computer keyboard cleaner) turned upside down and spray the thermostat with a few shots to make it cold. (USE EYE protection, i.e., safety glasses and keep your fingers out of the way!)
Switch red probe to left or
white/pale green wire slot
white/pale green wire slot
Refrigerator Defrost Thermostat (bi-metal contact)
The black wire is connected to the defrost heater element, and the middle white wire is connected to the heater element (splice).
If the reading is zero or infinity (no continuity, no beep) the heating element is bad and should be replaced.
If the reading is zero or infinity (no continuity, no beep) the heating element is bad and should be replaced.
Test the
Place a probe on each terminal. The multimeter should beep and/or display a reading somewhere between zero and infinity. If the meter indicates an open circuit (no continuity, no beep) or if the reading is zero or infinity --"0L." (open loop), the heating element is bad and should be replaced.
refrigerator defrost heating element
for continuity using a multimeter. Set the multimeter to the continuity setting. Some multimeter’s will display an actual number when in continuity mode, while others do not.Place a probe on each terminal. The multimeter should beep and/or display a reading somewhere between zero and infinity. If the meter indicates an open circuit (no continuity, no beep) or if the reading is zero or infinity --"0L." (open loop), the heating element is bad and should be replaced.
Put red probe in black wire slot, black probe in middle or white slot
I have removed the defrost heater and defrost thermostat assembly from the refrigerator to give you a better view. You can perform the test while the assembly is installed, simply unplug the plastic connector.
Refrigerator Defrost Heater Element
Unplug the plastic connector at the top of the coils (near the thermostat) by squeezing the connector lock handles with your index finger and thumb while gently wiggling the connector. Do not pull by holding the wires !
Test the defrost heater element and defrost thermostat by placing the multimeter probes in the two slots on the plastic connector as indicated in the next photos.
Test the defrost heater element and defrost thermostat by placing the multimeter probes in the two slots on the plastic connector as indicated in the next photos.
Close-up of Translucent Plastic Connector
Heater and Thermo-one unit in a series
Note: On the model used in this article, the refrigerator defrost heater element and the thermostat are sold as one unit and are connected in a series.
Located inside the freezer compartment behind the back wall panel.
See replace section for information on how to remove and replace.
See replace section for information on how to remove and replace.
Refrigerator Defrost Heater Element
and the
Refrigerator Defrost Thermostat (bi-metal contact)
Adaptive Defrost Control (ADC)
The adaptive defrost control basically does the same job as a defrost timer and more. Like the defrost timer, it shuts off the refrigerator cooling devices and redirects the power to the defrost heater for the defrosting cycle. It then redirects the power to the compressor and fans to come back on when the defrost cycle is over. Some also record and make calculations to help make the cycle more accurate.
If you need to locate the ADC in your refrigerator to check or replace it: Here are step-by-step instructions on how to locate and replace the ADC.
Defrost Timer
ADC
You can test the defrost timer for continuity. Set the multimeter as instructed above. Place one of the multimeter's probes on the common terminal. It should be labeled 3 or C.
If none of the terminals are labeled, you can locate the common terminal by determining which terminal coincides with the white wire in the connector plug. With one multimeter probe touching the common terminal, touch the other lead to the other three remaining terminals, one at a time. Testing the first pair should produce a reading of zero, or near zero, indicating continuity.
The second pair may also result in a reading of zero or near zero. Testing the third pair of terminals should produce a reading of infinity.
If none of the terminals are labeled, you can locate the common terminal by determining which terminal coincides with the white wire in the connector plug. With one multimeter probe touching the common terminal, touch the other lead to the other three remaining terminals, one at a time. Testing the first pair should produce a reading of zero, or near zero, indicating continuity.
The second pair may also result in a reading of zero or near zero. Testing the third pair of terminals should produce a reading of infinity.
Locate the defrost timer advancing screw *(timer switch) and turn it in a clockwise motion until it clicks. Depending on the timer (there are many styles), you can usually put a flat edge screwdriver in the slot to turn it (see top left of photo circled in red). Use the multimeter to test the terminals again in the same manner as described above.
Defrost Timer
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Have you changed all 3 parts, have them installed correctly--but still have the same problem?
The defrost timer is similar to a clock, and if the motor that advances it fails, the defrost cycle will not be started, or maybe it will stay in defrost and not go back into the cooling mode. [How to test the defrost timer coming up below in a few paragraphs]
Test the
The problem will most likely be with one part. However, several parts can go bad at once, (e.g., power surge, shorts, age). Start with the easy parts!
Test the
adaptive defrost control
by eliminating the other two possible problem parts. Some waste time by trying to "test" and "jump" the ADC terminals to see if the ADC is bad. This can be dangerous because you are working with a "live" (energized) circuit--you can get SHOCKED and possibly damage the ADC and other parts. This is easier--Remember: There are three (3) main things that can go bad with the defrost system. Two are relatively easy to access, test and replace--the defrost heater and thermostat. If the defrost heater and defrost thermostat test out okay, replace the adaptive defrost control. Start with the easy parts!The problem will most likely be with one part. However, several parts can go bad at once, (e.g., power surge, shorts, age). Start with the easy parts!
Defrost Timer and ADC are tested differently
Help!
Note: Testing Defrost Heater, Defrost Thermostat, ADC, and Defrost Timer on this page.
Also, see Compressor section for testing compressor and related parts. For Technicians Only
Also, see Compressor section for testing compressor and related parts. For Technicians Only
Back wall panel removed
Note: Larger computer screens will show larger materials!
Refrigerator Parts
Multimeter Testing
This is a FREE information site!
Part of EdDx Educational Series
Part of EdDx Educational Series
Multimeter Testing Refrigerator Parts
Analog
Digital
(right click to enlarge)
Refrigerator Defrost Heater Element
Testing the Defrost Parts
and the
Refrigerator Defrost Thermostat (bi-metal contact)
Located inside the freezer compartment behind the back wall panel. (removed)
See replace section for information on how to remove and replace.
See replace section for information on how to remove and replace.
In this test, one of the pairs of terminals should produce a reading of continuity. At least one pair, but maybe two, should produce a reading of infinity.
Please note that a pair of terminals that demonstrated continuity in the first test should now demonstrate infinity. Also, a pair of terminals that demonstrated infinity in the first test should now demonstrate continuity. If not, and the defrost heater and defrost thermostat test out okay, replace the timer.
Please note that a pair of terminals that demonstrated continuity in the first test should now demonstrate infinity. Also, a pair of terminals that demonstrated infinity in the first test should now demonstrate continuity. If not, and the defrost heater and defrost thermostat test out okay, replace the timer.
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©2016, 2023
©2016, 2023
Multimeter Testing-
Compressor and
Related Parts-
For Technicians Only
Compressor and
Related Parts-
For Technicians Only
Integrated Test Leads/Probes
Switched Multimeter
Auto-Ranging Multimeter
Multimeters come in different sizes, colors, and shapes. Multimeters can have different features and levels of sophistication. Some have the leads hard-wired to the unit and some have plug-in leads.
*Notes: Read the directions on how to use your multimeter that comes with your multimeter (for specific multimeter information and symbol meanings).
= ohms
= audible continuity
Multimeters
This is a multimeter>
You can buy an analog multimeter or a digital multimeter. You can get an inexpensive meter if this is a one-time-use item. You can use the multimeter to test batteries, switches and other appliances you might have. Check out a few ads in a magazine or your favorite websites to compare prices and features.
Some tests do require an accurate reading. Some cheap units are not accurate, but can do a simple continuity test on your refrigerator parts.
*(See notes at the bottom of this page.)
*notes on multimeter
A multimeter is an instrument used to check for voltage, resistance or continuity of electrical components and small amounts of current in circuits. It has its own power source, i.e.,a battery or batteries!
Caution: Unplug the refrigerator! These tests are conducted with the unit NOT being plugged in, i.e., NO ELECTRICITY!
Unplug the electric cord!
*
UNPLUG
Note:This is inside the freezer compartment from the front!
NOT the back of the refrigerator!
NOT the back of the refrigerator!
Note:This is inside the freezer compartment from the front!
NOT the back of the refrigerator!
NOT the back of the refrigerator!
Meter Readings
In electrical applications, when an electrical circuit is capable of conducting current, it demonstrates electrical continuity. It is said to be closed because the circuit is complete.
Test the multimeter (Use the continuity setting) to ensure that it is working properly by turning it on and touching the probes together - the meter should read zero. An indicator light might flash or a beeping sound might be heard, indicating a closed circuit. [The meter "beeps" so that you can probe for continuity without constantly looking over at the meter.] When the probes are not touching anything, the multimeter will read infinity, showing that the circuit is open [no beep].
Adaptive Defrost Control or Defrost Timer
Remember, your refrigerator can have one or the other, not both! You can tell by the model number or by taking the refrigerator apart--you decide.
I mention that here because this model had the ADC, but someone might be working on a model with a mechanical timer.
I mention that here because this model had the ADC, but someone might be working on a model with a mechanical timer.
Most multimeters come with instructions.
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You can hover over any link to see if it is an Amazon link, if this matters, or a link to a page on this website or to a reference page, e.g., Smithsonian Institution, bookmark on this website, etc.
*Disclosure: Some links on this website are associate links and are used to help illustrate what an item looks like, and you can decide if you want to just look or purchase the item. "As an Amazon Associate, I earn from qualifying purchases." We receive a small commission (that helps support this website) if you actually purchase from this company, but the price to you remains the same.
You can hover over any link to see if it is an Amazon link, if this matters, or a link to a page on this website or to a reference page, e.g., Smithsonian Institution, bookmark on this website, etc.
You can hover over any link to see if it is an Amazon link, if this matters, or a link to a page on this website or to a reference page, e.g., Smithsonian Institution, bookmark on this website, etc.