Tests on an AC unit with the best blower fan can be as simple as looking at the windings or as complex as checking the power and electrical circuit continuity. You might even learn more about the inner workings of the AC unit along the way because the procedure is simple and requires little effort.
There are many moving parts in an air conditioner unit, and any one of them could be defective, causing your device to stop working. Even an AC with the greatest blower fan can have problems, so fixing them is important. So, how can you tell if the blower motor is working properly or not?
The complete guide we’ve written on AC blower failure identification is provided below. This will provide you with the opportunity to address the problem right away, saving you both time and money in the process.
Signs and Symptoms of a Faulty AC Fan Motor
The part of the air conditioning system that is parked outside your home, the condenser unit, contains the AC fan. To check the fan through the condenser unit’s vents, you must go outside. The following are typical warning indications of a defective fan motor:
- Even with the AC on, the fan won’t turn on.
- Even with the AC turned off, the fan continues to run.
- Although the fan is turned on, the blades are moving slowly.
- When you turn on the fan, the condenser unit makes a rattling sound.
It might be difficult to determine whether the fan motor is to blame because these symptoms can signify a variety of issues, including faulty evaporator coils. It is important to understand how to test an AC fan motor for this reason.
Poor Airflow
One of the most noticeable symptoms of a failed blower fan is weak airflow. Typically, this happens because the motor eventually becomes weaker and is unable to blast enough cold or hot air. The motor will eventually stop working altogether.
Check the blower motor for any debris if you detect a decrease in the airflow of your air conditioner. Cleaning them out may fix the problem if all that’s preventing your AC from working correctly is dust and grime.
Excessive Heating
Sometimes your HVAC system may overheat, in which case you should have the device checked right away. One of the most serious motor failure symptoms, this one might cause a fire to start inside the AC unit. If you see this happening, it is essential that you act quickly.
Weird Noises
The AC unit begins to make odd noises when the motor’s internal components start getting worse over time. If you hear these noises, you might need to get in touch with an HVAC expert so they can inspect the equipment and make any necessary repairs. In rare cases, re-lubricating the fan’s belt and bearings may be sufficient.
How To Check AC Fan Motor With Multimeter
Try the following procedures to examine the blower motor once you’ve identified the warning indications mentioned above and are certain that it is the issue. You won’t have any trouble performing the pretty simple task of testing your AC blower motor.
Verify the power
Check the voltage at the transformer, control board, and power outlet as well. Make sure that a high voltage enters the system and that the board receives the proper voltage.
If the motor isn’t receiving electricity, a faulty control board can be the cause. To check whether the outlet is functional or not, simply test it with the motor.
Check The Continuity Of The Connection
The presence of dirt or debris indicates that the motor is shorted, and you may use a multimeter to check the continuity of the current going to the motor. If the circuit continuity is good, there will be little resistance from the positive terminal to the negative one. If not, the circuit probably isn’t finished.
Cleaning the blower might make it work again, but if it is seriously broken, you might need to call an expert to fix it.
The trigger for the Switch
Your HVAC system’s safety switch may have been activated by an open blower compartment door, stopping the engine from working. When the compartment door is correctly closed, the safety switch can be reset.
Check The Windings
The windings that serve as the motor’s internal electromagnets can be tested for resistance using thermostat monitors, and damage to them makes the motor useless. When the windings are operating properly, the thermostat should display a low reading.
A short in the windings is clearly indicated by a thermostat reading of zero. An infinite sign, on the other hand, denotes damage to them.
Test the capacitor that is attached
It’s possible that the capacitor won’t function as the motor expects, in which case a replacement is required. You can test the motor again after replacing the capacitor if it doesn’t meet the requirements.
As an alternative, you can test the component’s resistance using a capacitor. The maker of the HVAC unit has established that the microfarad reading must be less than 10% of the capacitance. If it is greater than 10%, the capacitor might need to be replaced.
Restart the blower
If everything is in order, you can try to reset the blower motor and try to start it once more. The motor may possibly start working correctly once more as a result of this.
Follow these steps to reset your AC blower motor.
- Shut Off the Power
Unplug your air conditioner from the outlet to turn off the power to it. Alternatively, you can shut off the breaker it is linked to if it is connected directly to the control board.
- Take the Cover Off
The screws holding the HVAC fan access panel in place can be removed. Before moving on, give the motor a chance to cool.
- Press The Reset Button
The red reset button for the blower motor is normally located on the motor’s back. It can be safely pressed because it is placed away from the direction where fans blow air.
The reset button might already have popped if the motor had become overloaded. Reset the motor by pushing it back in, and you are done.
Conclusion
In conclusion, using a multimeter to check an AC fan motor is a straightforward and valuable diagnostic technique for HVAC technicians and homeowners alike. This process allows you to assess the health and functionality of your air conditioning system’s fan motor, ensuring efficient cooling and optimal performance.
By following the step-by-step guide provided in this blog, you can identify issues such as motor winding problems, electrical faults, or motor capacitor failures. Regularly checking and maintaining your AC fan motor can help extend the lifespan of your cooling system, improve energy efficiency, and prevent costly breakdowns during the scorching summer months.
FAQs
What if I’m unsure about performing these tests myself?
If you’re not comfortable or experienced with electrical testing, it’s best to consult a professional HVAC technician or appliance repair specialist to diagnose and repair any issues with the AC fan motor.
Remember that the specifics of testing an AC fan motor may vary depending on the make and model of the motor and the HVAC or appliance system it is a part of. Always refer to the manufacturer’s documentation and safety guidelines when performing any electrical testing or repairs.
What should I do if the resistance readings are out of the specified range?
If the readings are significantly different from the specified range, it may indicate a problem with the motor windings. In such cases, the motor may need to be replaced or serviced by a professional technician.
How do I check the windings of the AC fan motor?
To check the windings, disconnect the motor from its power source. Then, touch the multimeter probes to the motor’s terminals. Check the resistance between Common and Run (R) terminal
Common and Start (S) terminals
Start (S) and Run (R) terminals