The purpose of the evaporator fan in a refrigerator is to circulate cold air from the evaporator coils throughout the food storage compartments. The evaporator coils are usually located behind the freezer compartment, and the evaporator fan should be right in front of them, although it may be offset to one side or the other.
The fan should come on whenever the compressor cycles on. If it doesn't, the refrigerator won't get cool enough to preserve your food. When this happens, the fault could be in the wiring, the control panel or the fan itself. It's fairly easy to perform a continuity test on the fan to determine whether or not you need to replace it.
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Do You Need to Test the Fan?
If your refrigerator isn't getting cool, the fan is just one of many possible reasons. According to Repair Clinic, other possible reasons include dirty evaporator coils, a faulty thermostat or a bad evaporator motor (compressor). A loud blowing sound from the motor doesn't mean it's bad either. You can often fix that by repositioning the refrigerator. That's the procedure for a Samsung refrigerator fan noise fix, according to Samsung.
If you don't hear any noise from the fan at all, and the evaporator motor and lights seem to be working normally, that's a pretty good indication that something is wrong with the fan. You'll want to test it to rule out a fault with the control panel or wiring.
How to Remove the Fan for Testing
On many refrigerators, the fan is hidden by the back freezer panel, but it may also be located behind its own shield in a corner of the freezer compartment. Before you try to access it, unplug the refrigerator and remove everything, including shelves, from the freezer compartment.
You may need to consult your owner's manual for details, but removing the panel or shield usually involves removing two or three screws and lifting it out. Once the fan is exposed, give the blades a push to make sure they're turning smoothly. If not, the test is complete. Replace the fan.
If the fan blades turn freely, unscrew the bracket holding the fan to the freezer wall and pull the electrical harness apart. Remove the fan and inspect the bushings on both sides to make sure they aren't worn.
Conducting a Continuity Test on an Evaporator Fan
To conduct a continuity test, you need a multimeter set to measure resistance in the 1-ohm (Ω) to 100-Ω range. Set the fan on a benchtop and locate the two power terminals, which is where the wires connect to the fan coil. Touch one of the tester leads to one terminal and the other lead to the other terminal and check the reading.
If you get a low resistance reading, which is anything less than about 100 Ω, the charge generated by the tester is circulating normally and the coil is good. If you get a very high or infinite resistance reading (which is denoted by OL on a digital meter), there's a break somewhere, meaning the coil is bad and the fan needs to be replaced.
If the fan passes the continuity test, you'll want to look for a problem in the wiring or control panel. At this point, it's probably a good idea to call a licensed service technician.