Extraneous noise, buzzing or Whistling sounds coming from a running refrigeration unit often signal that the cooling system is under increased load. In most modern models, especially in No Frost systems, the source of unpleasant sound is precisely fan. Over time, the factory grease in the bearings evaporates, thickens or mixes with dust, turning into an abrasive mass that causes friction and a characteristic hum.
Before looking for how to lubricate the mechanism, you must clearly understand that not all oils are suitable for operation at low temperatures. Using the wrong composition can lead to freezing of the unit, its complete blocking and, as a result, failure of the compressor or evaporator. In this article, we will look in detail at the types of lubricants that are compatible with the food industry and low-temperature conditions.
It is also important to consider that some modern fan motors are equipped with sealed, maintenance-free bearings. In such cases, an attempt to lubricate may not work, and the only solution will be to replace the entire assembly. However, in most situations, competent maintenance allows you to extend the life of the device for many years without expensive repairs.
Why does a fan hum and when is lubrication needed
The main cause of noise is an imbalance in the rotation of the blades due to increased resistance in the axis. When sliding bearing or the ball bearing loses its lubricating properties, metal begins to rub against metal. This not only creates acoustic discomfort, but also leads to heating of the bushing, which can melt the plastic seat.
Often users notice that the noise increases immediately after opening the door or, conversely, subsides. This is due to the algorithms of the electronics: when the door is opened, the fan can stop so as not to blow out cold, and when closed, it can start at maximum speed. If at this moment a grinding or cracking noise is heard, it means that the lubricant has completely dried out.
⚠️ Attention: If, when turning the blade with your finger, you feel a strong backlash or a clear misalignment of the axis, the lubricant will no longer help. In this case, the bearing has mechanical damage and requires replacing the entire motor.
Another factor is ice freezing on the blades or hub. In No Frost systems, this can happen when the defrosting heating element is faulty, but often an ice crust forms simply due to the entry of moist air during rare defrosting. Before pouring oil, make sure that the mechanism is completely defrosted and free of ice crystals.
Selecting a suitable lubricant
The question of how to lubricate a refrigerator fan is critical, since standard household oils are often not suitable for extreme operating conditions. Regular engine oil turns into a viscous gel or solid at a temperature of -18°C or -24°C, which instantly stops the fan. Therefore, the choice should fall on synthetic or special compounds.
The optimal choice is synthetic oils based on polyalphaolefins (PAO) or esters. They remain fluid at very low temperatures and do not evaporate quickly. Silicone lubricants, which are inert to plastic and rubber, often used in the construction of refrigeration fans, have also proven themselves well.
It is strictly not recommended to use vegetable oils, grease, lithol or conventional sprays such as WD-40 in their pure form. Vegetable oils polymerize over time and turn into a sticky mass to which dust sticks. WD-40 is an excellent solvent and moisture displacer, but a poor lubricant: it evaporates quickly, leaving parts dry, which accelerates wear.
| Lubricant type | Temperature range | Compatibility with plastic | Recommendation |
|---|---|---|---|
| Oil for sewing machines | up to -10°C | High | Not recommended (freezes) |
| WD-40 (spray) | to -50°C | Medium | For flushing only, not for lubrication |
| Silicone grease | from -60°C to +200°C | High | Recommended |
| Synthetic oil (PAO) | from -50°C to +150°C | High | Optimal choice |
Necessary tools for maintenance
To carry out high-quality fan maintenance work, you will need a minimum set of tools that any craftsman can find in his home. The main thing is to provide access to the assembly and carefully apply the compound without damaging the motor winding or plastic fasteners.
First of all, you will need a screwdriver. Depending on the model of the refrigerator (Indesit, Atlant, LG or Bosch) it can be a Phillips PH2 or flat slotted screwdriver. To remove some plastic latches, you may need a knife with a wide blade or a special plastic puller to avoid scratching the case.
To apply lubricant, it is best to use a medical syringe with a blunt needle or an oil can with a thin spout. This will allow a drop of oil to be delivered precisely into the gap between the shaft and the bushing, without splashing chemicals onto adjacent parts. Also prepare a rag and a degreaser (alcohol or isopropanol) for pre-cleaning.
☑️ Preparation for lubrication
Step-by-step instructions: how to lubricate the fan
The maintenance process begins with completely disconnecting the refrigerator from the power supply. This safety requirement is mandatory as you will have to work in close proximity to electrical contacts and possibly a damp environment after defrosting.
Next you need to gain access to the evaporator. In refrigerators with a No Frost system, the back panel in the freezer compartment is removed for this purpose. The panel can be attached with screws or held on with plastic latches. After removing the panel, you will see the evaporator and the fan located next to it. If there is ice on the parts, let the refrigerator stand defrosted for several hours.
The fan itself is usually mounted on a bracket or directly on the duct housing. Disconnect the power connector (chip) and unscrew the fastening screws. Remove the motor. Now the most important thing: you need to remove the protective sticker from the back of the engine (shaft side) to get to the bearing. Under the sticker there is often a locking ring or a rubber plug.
⚠️ Attention: When removing the locking ring, hold the shaft with your finger so that it does not go deep inside the motor housing. It is easy to lose it, and it can be difficult to find and return it to its place without a special tool.
Apply 2-3 drops of the selected lubricant to the shaft, turning it by hand to distribute the composition inside the bushing. Do not pour too much oil as excess oil may leak and stain food or plastic. Reassemble everything in the reverse order, making sure that the wires do not get under the blades.
What to do if the sticker does not come off?
If the sticker is glued tightly, you can carefully pierce it with a thin drill or needle right in the center of the shaft and pour oil through the hole. This is less aesthetically pleasing, but functionally effective.
Typical mistakes when lubricating a refrigerator
One of the most common mistakes is using graphite lubricant. Despite its excellent anti-friction properties, graphite conducts electricity. If graphite gets on the motor contacts or control board, it can cause a short circuit and failure of the electronics.
Another mistake is lubrication without preliminary cleaning. If you drop new oil on top of old, dried dirt and lint, you will simply create an abrasive paste that will accelerate wear on the rubbing parts. Always first clean the shaft with alcohol or Galosh gasoline, removing all deposits.
Also, do not try to lubricate the fan without removing it from the refrigerator if it is difficult to reach. A drop of oil that gets on a plastic box or insulation can cause them to deteriorate over time, not to mention the risk of getting on food.
Checking the result and diagnostics
After assembling and turning on the refrigerator, do not expect instant silence. Let the equipment run for 10-15 minutes so that the lubricant is distributed over all rubbing surfaces. If the noise has become quieter, but has not disappeared completely, you may need to repeat the procedure in a couple of days.
Pay attention to vibration. If the fan is lubricated, but the refrigerator body vibrates more than usual, you may have poorly secured the panel or the motor itself. Check that all screws are tight. In some cases, vibration is transmitted to the air ducts, and then installing additional damper pads helps.
If after lubrication the nature of the sound has changed, but the problem remains, check the balancing of the blades. Sometimes one of the blades can become broken or deformed, causing it to wobble. In this case, only replacing the impeller or the entire fan assembly will help.
When lubrication no longer helps
There are situations when the question of “what to lubricate” is already is not relevant, since the node resource is completely exhausted. If you observe sparking inside the motor, a burning smell, or feel that the shaft is spinning with enormous force even after cleaning and lubrication, the bearing is destroyed.
In addition, modern compact fans often use sintered bronze bushings that are impregnated with oil at the factory. When this impregnation is developed, the structure of the bushing changes, and it begins to “eat” the shaft. In this case, lubricant will only give a temporary effect for several days or weeks.
The cost of a new refrigerator fan is usually low, and replacing it takes 15-20 minutes. Therefore, if the lubricant does not help, do not waste time experimenting with exotic compounds, but simply replace the part with an original one or a high-quality analogue.
⚠️ Attention: When buying a new fan, pay attention to the direction of rotation of the blades and the length of the shaft. They may differ from one manufacturer to another, even if the motors are similar in appearance.
Can oil be used for two-stroke engines?
It is not recommended to use oil for two-stroke engines. It is intended for combustion in the combustion chamber and contains additives that can be aggressive to plastic and rubber, and also have a specific odor that can be transferred to products.
How often should the fan be lubricated?
Preventive lubrication is recommended no more than once every 3-5 years, depending on the intensity of operation of the refrigerator. Frequent lubrication is not required if high-quality synthetic materials are used.
Is it dangerous to get silicone grease on food?
Food grade silicone lubricants are inert and inert, but technical silicone may contain harmful impurities. In any case, direct contact of any lubricant with food is undesirable, so carefully isolate the work area.
Why does the fan make noise immediately after defrosting?
If the noise appeared immediately after defrosting, it is possible that water got into the bearing and washed away the remaining lubricant, or ice blocked the blades. Let the refrigerator dry and run idle for several hours.
What is the difference between lubricant for sliding and rolling bearings?
Sliding bearings (bushings) require more fluid oils that create a film. For ball bearings (rolling), you can use thicker greases, but in refrigerators it is bushings that require a liquid composition that are most often found.