Modern refrigerators operating using the No Frost system are completely dependent on forced air circulation inside the chambers. If you notice that food in the freezer compartment has stopped freezing, and ice has formed on the back wall of the main chamber, this is a sure sign that the air flow has stopped. Often the cause is a failure of the evaporation fan electric motor, which can be diagnosed independently.
To accurately determine the malfunction, it is not enough to simply twist the blades with your finger, since the problem may be hidden in the electrical part of the motor. Use multimeter allows you to determine with high accuracy the integrity of the windings and the absence of a short circuit. In this article, we will analyze a detailed algorithm of actions that will help you understand whether the unit requires replacement or repair is possible.
Before you begin disassembling the unit, you need to make sure you have basic tools and follow safety precautions. Working with electrical appliances requires care, and diagnosing small parts requires accuracy. We will consider all stages: from preparing the device to interpreting the received readings on the tester scale.
Preparation for diagnostics and safety precautions
The first and most critical stage is to completely disconnect the refrigerator from the electrical network. You cannot rely only on the shutdown button, if there is one on the case; you must unplug the plug from the socket. This eliminates the risk of electric shock and prevents damage to the control electronics if the probes are accidentally shorted.
Next you will need to provide access to the fan, which in No Frost systems is usually hidden behind a plastic panel in the freezer. To dismantle the trim, you often need different types of screwdrivers, including Phillips and flathead, as well as a knife to carefully pry up the latches. It is important not to damage the fragile plastic, which becomes especially brittle in the cold.
⚠️ Attention: Before removing the panels, be sure to defrost the refrigerator for 10-12 hours if there is ice inside. An attempt to tear off a frozen panel by force will lead to breakage of the plastic fasteners or damage to the evaporator tubes.
To carry out measurements, prepare a digital multimeter. Make sure that the bateria in the device is charged and that the probes have no insulation damage. The mode switch must work clearly, without backlash, so that the readings on the display are correct and reliable.
☑️ Preparation for testing
Access to the fan and visual inspection
After defrosting and removing all the shelves in the freezer, you need to dismantle the back wall. In different models of refrigerators Indesit, Atlant or LG this process may differ: in some places you need to unscrew the visible screws, and in others you need to carefully unclip the hidden fasteners. The main thing is to act without excessive force so as not to break the guides.
When the panel is removed, you will see the evaporator and the fan located next to it. Before removing the motor, perform a thorough visual inspection. Pay attention to the condition of the blades: they must be intact, without cracks or chips. Any imbalance of the impeller can cause noise, which users often confuse with a breakdown of the motor itself.
Check that the shaft rotates freely. If, when scrolling by hand, you feel jamming, a stiff move, or hear a metallic grinding sound, it means that the bearings have exhausted their service life. In such a situation, even a working electrical part will not allow the fan to operate normally, and the unit must be replaced.
Inspect the wires going to the motor. There should be no traces of melting, kinks or damage to the insulation. Often problems arise not in the motor itself, but in the place where the connector is connected, which could be oxidized by moisture or condensation.
Setting up a multimeter and measurement modes
To check the integrity of the motor windings, we need a resistance measurement mode, which is indicated on the instrument scale by the symbol Ohm (Ω). In most household multimeters, this sector has several measurement limits: 200, 2000, 20k, and so on. For diagnostics of refrigerator fans, a limit of 2 kOhm (2000 Ohms) is usually sufficient.
If your multimeter does not have an automatic limit selection, set the switch to the minimum value, for example, 200 Ohms, to start, and increase the range as necessary. Also useful is the dialing mode, indicated by a speaker icon that beeps when the circuit is closed. This allows you to carry out quick diagnostics without being distracted by numbers.
Before starting measurements, be sure to check the functionality of the tester itself. Connect the probes to each other: zeros or a value close to zero should appear on the display, and a squeaking sound should be heard in the dialing mode. If the device shows one or infinity with the probes closed, its battery is low or the device is faulty.
Algorithm for checking the windings motor
To ring the fan, you need to disconnect its connector from the control board or terminal block. Measurements made without disconnecting the refrigerator from the network will be incorrect, since the current will flow through other elements of the circuit. Carefully remove the chip with the motor contacts.
Attach the multimeter probes to the motor contacts. Polarity in this case is not important, since we are measuring the active resistance of the winding. If the fan has two leads, simply touch them with the probes. If there are more pins (for example, three or four), the test circuit may be more complex and depend on the type of motor.
In the case of a conventional two-pin motor, a working condition is characterized by the presence of a certain resistance. The numbers on the screen may vary depending on the wattage and model, but they typically range from 100 to 800 ohms. The absence of readings (one in the most significant digit) indicates a winding break.
Critical important: If the multimeter shows a resistance close to zero (0-2 Ohms), this indicates an interturn short circuit. Such a fan cannot be operated, since when connected it will trigger the protection or the control board fuse will blow.
Table of typical faults and indications
Interpretation of the device readings requires an understanding of what exactly we see on the display. Different resistance values indicate completely different physical processes inside the engine. Below is a table that helps classify the condition of the node based on the measurement results.
| Multimeter reading | Measurement mode | Diagnosis | Actions |
|---|---|---|---|
| 1 (infinity) | Resistance (Ω) | Winding break | Fan replacement |
| 0 - 5 Ohm | Resistance (Ω) | Interturn short circuit | Fan replacement |
| 100 - 800 Ohm | Resistance (Ω) | Normal (defective) | Check the power circuit |
| 0 (with sound) | Continuity test | Short circuit | Replacing the fan |
It is worth noting that in some complex motors with multiple windings (for example, for different rotation speeds), the resistance between different pairs of contacts will differ. In such cases, it is necessary to have on hand the technical documentation for a specific model Whirlpool or Boschto know the reference values.
If the electrical part is normal, but the fan does not start when voltage is applied, the problem may be mechanical. A jammed shaft or dry grease in the bearings creates a load that the motor cannot overcome. In this case, the multimeter will show the norm, but such a detail is of little use.
Checking the power circuit and control signal
There are situations when the fan itself is working, the windings are intact, the shaft rotates easily, but there is no cold in the chamber. This means that there is no voltage being supplied to the motor. In this case, it is necessary to ring not the engine, but the circuit going to it from the control module.
For this check, you will need to plug in the refrigerator (being extremely careful!) and measure the voltage at the connector where the fan is connected. Attention: polarity and the correct choice of mode are already important here - direct current (DCV), usually within 20 Volts.
If there is voltage (for example, 12 Volts) and the fan is standing, it means that it is still faulty, despite the normal resistance of the windings (the graphite brushes may have worn out or the commutator is stuck). If there is no voltage, the problem lies in the control board, temperature sensors or defrost timer.
⚠️ Attention: Be extremely careful when measuring voltage under load. Do not touch the exposed parts of the probes and metal parts of the refrigerator at the same time to avoid electric shock.
A common cause of no power is a malfunction of the defrost sensor. If the control module “thinks” that a defrosting process is in progress, it forcibly turns off the fan. Therefore, diagnostics should always be comprehensive.
Why can the fan run jerkily?
If the fan jerks or works intermittently, this may indicate poor contact in the connector or beginning wear of the bearings, which periodically jam the shaft. Also, the cause may be unstable voltage from the control board.
Replacing a faulty fan
If checking with a multimeter shows an open or short circuit, the only correct solution is to replace the unit. Repairing the windings at home is impossible due to the microscopic diameter of the wire and the need for special impregnation with varnish.
The new fan must match the original in geometric dimensions, shaft diameter, supply voltage and direction of rotation. Pay attention to the markings: the voltage is usually indicated on the housing (for example, 12V DC or 220V AC) and the direction of rotation with an arrow.
Installation is performed in the reverse order: connect the connector, secure the motor in the seat, install the impeller and close the panel. Don't forget to check whether the blades are touching the walls of the box or ice.
Frequently asked questions (FAQ)
Is it possible to lubricate the fan instead of replacing it?
Lubrication is only possible if the problem is exclusively in the tight rotation of the shaft, and the electrical part is fully operational. However, most modern fans use sealed bearings that are not designed for maintenance. An attempt to drill a hole and drip oil often gives only a temporary effect for a couple of weeks.
Why does the new fan hum but not spin?
Most likely, the polarity of the connection is reversed if the motor is DC. Or the new fan shaft has a manufacturing defect and is jammed. Also, the reason may be insufficient voltage from the control board, which cannot break the rotor from its place.
What resistance should a 220 volt fan have?
The resistance of the windings of a 220V AC motor is usually higher than that of 12-volt analogues, and can range from 300 to 1500 Ohms and more, depending on power. You need to look for exact data in the specification of a specific model.
Does a fan malfunction affect the operation of the compressor?
Yes, it does indirectly. If the air does not circulate, the evaporator quickly becomes overgrown with ice, heat exchange is disrupted, and the compressor begins to work non-stop, trying to gain temperature. This leads to its overheating and increased energy consumption.