Troubleshooting and Changing Motors in HVAC

Chris Beaton is the proprietor of eMotors Direct, a web-based electrical motor retailer revolutionizing the way in which HVAC Technicians buy their motor replacements. Their 45 years of expertise, a workforce of motor consultants, and entry to North America’s main manufacturers put a wealth of data proper at your fingertips.  

Motors are the center and soul of HVAC programs, whether or not the system solely has one or it has many. As such, motors are additionally the principle motive an HVAC system stops working adequately or in any respect. When your consumer’s system isn’t offering sufficient warmth, cooling air, or it’s simply appearing unusual, you wish to establish and repair the problem rapidly so you may get the environment of their house, workplace, or constructing again to comfy as quickly as attainable. 

Indicators of HVAC Motor Failure

There are just a few indicators to search for when attempting to detect motor failure. Utilizing your senses, do the next HVAC system checks.

• Pay attention: How is the motor operating? Is it easy and getting up to the mark rapidly? Or is it squeaking, grinding, and weak? Unusual sounds can imply the bearings are worn or there are unfastened parts within the motor. 
• Really feel: The primary signal of motor failure is normally low, weak, or no airflow on the vents.
• Really feel: Really feel the skin of the motor for overheating and vibration.
• Odor: An overheated motor will give off a burning odor. 
• See: Visually examine the motor for a buildup of particles which may be stopping the motor from off-putting warmth.

Moreover, your consumer could have observed an uncommon enhance of their power payments. Which means the motor has needed to work a lot tougher to maintain up with the calls for of the system. 

Troubleshooting Your HVAC Motor

With out common upkeep and inspection, a motor would possibly carry your complete HVAC system to a halt. Under are the steps to troubleshooting and <hvac motor=””> (hyperlink to How HVAC Motors Work article).hvac>

Motor Inspections – Exterior

In the beginning, be sure that energy is reaching the motor. When a motor stops operating, it may possibly appear to be the motor itself is at fault, however that isn’t all the time the case. Unfastened connections and corroded contacts can stop energy from reaching the motor because it ought to, inflicting the motor to run poorly or in no way. There are lots of causes a motor received’t run that aren’t essentially brought on by the motor itself. You’ll want to examine the complete system, together with relays, capacitors, fuses, circuit breakers, switches, and so on. Are any “blown” or “tripped?” Use a multimeter to double-check that the resistance throughout these units is at zero. 

Testing if energy is reaching the motor is easy. Utilizing a multimeter, confirm the voltage current on the motor’s enter terminals. The studying ought to match the voltage ranking of the motor nameplate. If the voltage is right on the motor and the efficiency concern continues to be current, it’s time to close off the facility to the motor to finish additional examination. 

Security Be aware: Each precaution needs to be taken when working with excessive voltages to keep away from the chance of significant damage. Make sure that no energy can attain the motor whereas performing the next inspections. If the motor continues to be sizzling from operating, enable it to chill down earlier than persevering with. 

Manually (by hand) rotate the motor shaft. If it doesn’t rotate freely, the motor could also be jammed which will be brought on by the load or defective or worn bearings. If the shaft is simply too unfastened or wobbly, that is additionally an indication that the bearings are worn or broken. If the shaft rotates easily and with out jams, it’s time to examine the motor’s internals.

Motor Inspections – Inner

If the right energy is reaching the motor and the shaft strikes freely because it ought to. Now it’s time to start out testing a very powerful element of the motor’s inside circuit, the motor windings. 

Electrical motor windings can fail in both an open circuit or quick circuit state, and neither will enable the motor to proceed operating. To check for these failures, we’ll test the resistance of the motor windings. Utilizing a multimeter within the ohm setting, you’ll check the resistance between the widespread wire and the velocity wire, making certain you check every velocity wire for multi-speed motors. Double-check the beneficial resistance ranking with the producer.

An “OL” studying implies that the winding has failed in an open-loop state. That is an indicator that the windings have burnt and cut up aside and the motor wants substitute. A “0.00” studying implies that the winding has failed in a brief circuit state. That is an indicator that the winding insulation has melted, and the windings have fused or shorted out and the motor must be changed. 

If the readings match the manufacturer-recommended ranking, check to see if the velocity wire has grounded to the motor physique. This may be examined with the multimeter as effectively. If the velocity wire has grounded to the physique, the multimeter will learn “OL” when examined between the velocity wire and the motor body. 

Try this podcast discussing operation of some motors used within the HVAC business 

Most of the HVAC motors you’ll encounter are outfitted with a number of capacitors. If you happen to encounter a failed motor with a capacitor and you’ve got already accomplished the above inspections, the problem might be the capacitor. Very like the motor windings, capacitors can fail in open circuit or quick circuit states, and each received’t enable the motor to function correctly.

First, it is advisable to match the capacitance ranking of the capacitor to the beneficial ranking discovered on the motor’s nameplate. A capacitor that’s too small won’t present sufficient torque to start out the motor. If the scores match, discharge the capacitor earlier than finishing the next checks. A capacitor can maintain a cost for a while even after being disconnected, this cost is sufficient to trigger severe damage to the operator.

Take away the capacitor from the circuit and visually examine for put on and injury. Cracks, swelling, and leaking fluid all point out a defective capacitor that wants substitute. If the capacitor seems fantastic, check the capacitance worth. Utilizing a multimeter with a microfarad operate to check the capacitance throughout the terminals, the studying ought to match the ranking on the capacitor. If the studying is low, open circuit, or quick circuit, it’s time to interchange the capacitor.

ECM Motor Particular Inspections

In the case of ECM motors, you’ll full the above exams however first, it is advisable to examine the electronics module. The electronics module is most frequently discovered within the again finish of the motor. Disconnect the module and permit it to take a seat for a second to present the capacitors time to discharge. Visually examine the module for indicators of failure or injury. If you happen to discover any blackened, cracked, or swollen parts, a complete new substitute motor is required. If the module seems fantastic, reconnect it. 

Subsequent, utilizing the multimeter, check that voltage is current on the 24V widespread supply wire. If the right voltage is reaching the motor, check every velocity wire by connecting them one by one to the 24V widespread wire and operating the motor. If there is no such thing as a motion, check every winding as per the inner motor inspections part.

Changing HVAC Motors

After totally inspecting the motor and finishing the above troubleshooting ideas, it is possible for you to to find out if the motor will be repaired or must be changed. Changing the HVAC motor generally is a troublesome process, particularly in the event you don’t know what you might be in search of. Right here’s find out how to make it easy. 

First, it is advisable to know why the outdated motor failed. You will need to make sure that the brand new motor is as much as the duty at hand to keep away from the possibility that the brand new motor will fail in the identical method. Want a bit of additional assist with this? Your provider ought to have consultants on employees that will help you together with your electrical motor initiatives. 

Find the motor’s nameplate and transcribe the scores or take an image to keep away from any errors. Scores and options it’s best to pay attention to are:

• Diameter of the motor physique and the way it mounts
• Path of rotation
• Horsepower (HP)
• Voltage (V)
• Variety of speeds and their RPM scores
• Capacitor sizes
• Model (particularly in case your consumer has a most popular model)

Upon getting famous the vital scores and options, present this key info to your motor provider. They may get again to you with a quote on a brand new motor suited in your utility. If you happen to’re the kind who likes to analysis for your self, there are up and coming on-line platforms that assist you to simply discover OEM and direct replacements in your HVAC motors. You merely enter the required info and also you’re proven all of the motors that suit your utility, even serving to you discover cheaper choices with faster supply instances. 

Abstract

Motors are the commonest supply of HVAC system failure. Understanding how they work and what causes them to fail places you better off for troubleshooting the electrical motors you encounter. Unsure the place to start out? Comply with the above troubleshooting information to seek out the supply of your failure and decide if restore or substitute is the most suitable choice. 

When substitute is required, know which scores it is advisable to carry to your provider so you could find a substitute rapidly and at an ideal value – holding your prospects glad with you and your organization. 

Chris Beaton

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