There is a Refrigerator PTC Relay that needs to be tested.
The start relay is known as the positive temperature coefficient relay, and it may be malfunctioning if your refrigerator stops producing cold air.The compressor inside the fridge is started by the relay of the PTC.If you need to replace the PTC relay, you can easily check it.To make sure the ports have a low resistance, use a multimeter after you access the compressor and relay.The compressor may need to be checked if the relay still works.
Step 1: Plug your fridge in.
If you want to access the power cable, pull your refrigerator away from the wall.Someone can help you pull the fridge out if you can't do it on your own.If you want your fridge to have no power, you have to remove it from the outlet.You can keep your food in your fridge for up to 4 hours and in the freezer for 48 hours without power.The doors should not be opened to prevent it from heating up.If you expect your repairs to take longer than 4 hours, you should move your food to a different fridge or cooler.If your fridge is malfunctioning and you don't know how long it's been, you should throw away your food.
Step 2: To access the relay, remove the lower back panel from the fridge.
There is a small access panel on the back of the fridge.To remove the screws holding the panel in place, use a screwdriver and place them in a bowl.The back panel is out of the way when you are working.You don't have to remove the entire back of the fridge.
Step 3: If the relay has a plastic cover, take it out.
There is a large black cylinder on either side of the fridge compressor.There is a black plastic box on the side of the compressor that has wires coming out of it.Carefully remove the plastic cover from the compressor to expose the relay inside.You may need to use a screwdriver to open the tabs on the plastic cover.The relay may not have a plastic cover.
Step 4: The wires need to be disconnected.
The relay is attached to the side of the compressor and has wires running to it.Attach the ends of the wires to the relay with a pair of pliers.You need to remove the relay from each wire.The screw on the relay may have a wire attached to it.Before pulling the wire out of place, loosen the screw with a screwdriver.
Step 5: Pull the relay off of the wires.
Carefully remove the wires from the compressor's prongs, then grab the relay on the side.If you want to test it, you should remove the relay from the compressor and then use it.Push the compressor off of the prongs if you can't pull the relay easily.Don't pull the relay if it bends or breaks the compressor's prongs.
Step 6: If the relay is shorted look for burnt marks around the ports.
If there are any charred marks around the ports where it plugged into the compressor, inspect the relay.If you see burnt parts on the relay, it most likely needs to be replaced.Continue testing if the relay is intact.If the relay is shorted, you may be able to smell char on it.
Step 7: Set up a multimeter.
If you set your multimeter to read resistance in ohms, you can easily test the relay.You can use the black and red probes if you plug the end of the red probe into the positive terminal.A multimeter can be purchased from a hardware store.
Step 8: The probes should be placed in the M and S slots on the relay.
The ports on the side of the relay that have the letters M and S above them are the ones that connect to the compressor.If you want to check the reading on your multimeter, put one of the probes into each slot on the relay at the same time.It doesn't matter which probe you put into which port.The reading should read "open line", which means there is an infinite level of resistance between the 2 ports.The relay is upside-down if the reading doesn't say "OL"
Step 9: If the resistance changes to 0-1 ohms, you can flip the relay upside-down.
When you turn the relay over to the other side, keep the probes inside of the same ports.The relay is still working if the meter has a reading between 0-1.It may be time to get a replacement if the reading is above 1.When there is an electrical current running through the relay, a small metal piece moves.The metal piece closes the line and creates resistance.If the relay has correct readings, you should check the compressor next to it to see if it is causing the problem.
Step 10: If the resistance doesn't read OL or 0-1 ohms, you should replace the relay.
If your reading was over 1, you will have to replace the relay.Buy an exact match for your refrigerator from the model number listed on the side of the relay.Plug the new relay into the compressor's prongs once you get it.Attach the wires back to the relay so it can turn on the compressor again.Make sure the new relay works before you put it on the back panel.You can buy replacements from appliance specialty stores.They cost anywhere from $20 to 80USD.If you can't find the model number on the relay, you should look for the refrigerator model you have to buy a piece that fits inside.If you want to make sure the compressor isn't the cause of the problem, try testing it.
Step 11: The probes of a multimeter are on the left and right side of the compressor.
The relay plugs into the side of the compressor.If you want to take a resistance reading, put one probe furthest to the left and the other on the right.Don't forget the measurement if you write it down.The prongs will be shaped like a triangle.For the first measurement, use the prongs that are horizontally across from one another.The fridge model and compressor will affect the resistance between the 2 prongs.
Step 12: Take the resistance between the leftmost and the third prong.
Continue to hold one of the probes against the compressor.If you want the probe to be on the top or bottom, move it to the third pin.Between the 2 prongs, take a resistance measurement.The third prong will be on the bottom if the prongs are configured in an upside-down triangle.The third prong will be on the top if they form a right-side up triangle.Hold the probes for at least 10 seconds until the resistance settles on a single reading.
Step 13: The measurement can be found from the rightmost and third parts.
Move the other probe so it is on the rightmost one.If you want to get an accurate reading, keep the probes on the multimeter for at least 5 seconds.To find the resistance measurement, check the multimeter and write it down.
Step 14: If you add the lowest two readings, you can see if they are within the largest reading.
Add the 2 smallest resistance readings from the compressor together to find the total.Take the highest resistance measurement and divide it by the sum of the 2 readings to see how close they are.The compressor is okay if the sum of the 2 readings is less than the highest reading you took.If the readings are higher than the threshold, you need to call someone to fix the compressor for you.If the compressor is expensive to fix, you may want to buy a new one.There could be a problem with the internal fan if the compressor still works.If you have a problem with your fridge, contact a repair person.