The Importance of Proper Maintenance of a Fan Motor

Fan Motor

The Importance of Proper Maintenance of a Fan Motor

A fan motor is a crucial component of an air conditioning unit. It contains start capacitors to give it energy to get started and run capacitors that keep it running.

Nidec’s high-air capacity fan motors provide excellent cooling performance and low-level noise to meet market needs. They are also efficient and environmentally friendly.


Whether in the condensing unit of an air conditioner or a fan in your home, a well-functioning cooling fan motor plays an important role in maintaining your HVAC system and making sure you enjoy a comfortable indoor environment. If a cooling fan motor becomes overheated, however, it could cause damage to your air conditioning system and leave you with little or no cool air. Luckily, overheating is preventable with regular cleaning and maintenance of your AC fan.

In order to work reliably, fans for motor cooling must meet the same requirements as the main motors they are used to cool. That is why all fans for motor cooling from ZIEHL-ABEGG are designed and built so that they offer maximum flexibility in terms of voltage and frequency. In addition, large pressure increases can be accommodated, and the ventilation modules are also suitable for applications with special corrosion protection or explosion protection.

Since the cooling fan motor is responsible for rotating the blades that create the air flow, it must be able to handle high loads without overheating. If the motor fails to function properly, it will disable the blades and prevent air from passing through the radiator. A bad cooling fan motor can also lead to overheating, which will often cause the fuses in the cooling circuit to blow. These blown fuses are a clear indicator that there is an issue with the motor and should be serviced as soon as possible to avoid further issues.


Fan motor noise can be a nuisance and can be caused by several issues. Unbalanced blades, dry bearings, and loose fan light can all cause rattling noise. The rattling noise usually happens when the fan is turned on at higher speed settings. Keeping the motor properly lubricated can prevent this.

Two primary sources of fan noise are windage and magnetic. Windage noise is the major source of noise for two- and four-pole motors, while magnetic noise Fan Motor tends to be the major source of noise for six- or more-pole motors. Magnetic noise is caused by the unequal air gap between the rotor and stator, which can deform the stator, rotor and frame as well as generate electromagnetic vibration.

The contour of sound power level distribution under stall condition is shown in Figure 8. High noise occurs in three impeller passages, while other channel outlets show a reduction of noise. The stall cell propagates to the volute tongue, and causes periodic pressure and velocity fluctuations and induced high rotational noise. This noise is superimposed on the vortex and volute tongue noise, resulting in a high noise area.

The noise levels of fans are usually reported as the average of the dBA value for eight different octave bands. These octave band values are based on the measured radiated sound at the fan outlet or inlet. They do not include the effects of fan installation and local environmental noises, which must be estimated separately. To convert Lw to Lp, additional factors such as directivity, distance and control position must be taken into consideration.


Traditionally, fans are only evaluated for airflow and pressure rise. However, with energy efficiency legislation requiring more scrutiny of equipment costs, fan efficiency has become an important selection factor. The problem has been that the energy consumption of a fan is a bit complicated to determine, and is often misunderstood by engineers.

For example, the amount of power used by a fan motor depends on what it does with the energy that it receives from the electrical grid. This includes not only electrical losses in the motor windings and bearings but also friction within the shaft itself. Consequently, to get 746 watts of usable power out of a 1-HP motor, you actually have to put in somewhere between 867 and 1,008 watts of electrical power.

Another factor that drives power usage is the motor’s service factor which is a number that indicates how much overloaded it can be without sustaining damage. This factor is primarily a function of temperature and air velocity, so it will vary over the course of the year.

Lastly, a motor’s overall efficiency is determined by the combination of its fan and motor efficiency. This value is often referred to as FMEG (Fan and Motor Efficiency Grade) and is calculated by multiplying the fan and motor efficiency percentages together. It is important to remember that FMEG values are typically stated under standard air conditions. As a result, the actual performance of a fan under any other conditions will likely be different from that indicated by the FMEG rating.


The fan motor in your air conditioner is one of the most essential parts of the whole system. It’s under heavy stress for much of the year in Georgia, so keeping it in good shape is important to avoid more serious problems with your home’s AC unit.

If your fan motor is making a buzzing or rattling sound, it’s an indication that something is caught inside the unit and needs to be cleaned out. A rattling noise can also point to a wire that’s Fan Motor loose or not properly connected, but it’s best to call in a professional to do the work since electrical issues are dangerous for an untrained homeowner.

If your fan blades are stuck, it’s a good idea to lubricate them once in a while. You should always make sure the power to your fan is turned off first, and you can use a tool like a screwdriver to open up the cover of your fan motor to find the washers that need lubricating. Once you have the washers out, you can use any type of lubricating oil (we recommend using a small amount) to grease them up and get the fan blades spinning again. It’s a simple maintenance job that can help you save money on AC repairs down the road.