How to Cross Reference an OEM Motor

Key Takeaways

• Cross-referencing saves money: Skip the OEM markup by going directly to motor manufacturers or suppliers for replacements
• Two methods work best: Use either the manufacturer’s model number (quickest) or match motor specifications when the model number isn’t available
• Critical specs to record: Electrical ratings (HP, voltage, RPM), physical dimensions (frame size, mounting type), and application type ensure proper replacement
• Documentation is key: Always photograph the nameplate and record all visible specifications before ordering a replacement motor

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At the original installation, all HVAC equipment comes with the electric motors already installed. The OEM purchases motors from manufacturers you likely know to use in the design and build of their HVAC systems.

We know that electric motors are most often the reason an HVAC system is operating poorly or not at all. But that doesn’t mean you have to replace the whole system. You only need to find the OEM replacement for the motor.

Why Not Purchase From the OEM?

You purchased the HVAC system from them, why wouldn’t you go back to the original equipment manufacturer (OEM) for your motor replacement?

There are a few reasons why you would choose to purchase your motor replacement elsewhere.

Save Money!

The OEM purchases the motor directly from the manufacturer. They then mark up the price to ensure that they also make money on the sale.

You can save money by skipping the OEM of the HVAC equipment and going directly to the manufacturer or supplier of the motor.

Availability

By going directly to the motor supplier, you can save time by selecting a motor that is available immediately.

If the OEM of the HVAC system doesn’t have availability, they’ll need to order the motor before sending it on to you. In most cases, you should be able to find a replacement motor that can be shipped or picked up that day.

Brand Loyalty

You or your client may have a preferred electric motor brand and choose to have brand consistency across all stock.

This isn’t necessarily about one brand being better than the other. It’s about decreasing your spare inventory. When you select one brand to work with, you no longer need to keep as many spares on hand for replacements.

Cross-Referencing OEM Motors

How do you find the same motor but from a different brand? Here are two simple ways to cross-reference your OEM motor to find direct replacements.

Manufacturer Model Number

The simplest, quickest, and most accurate way to cross-reference your OEM electric motor is by using the motor manufacturer’s model number.

You’ll most often find the model number on the motor’s nameplate.

Remember, though, that many motor nameplates have a few different identifying numbers. HVAC system manufacturers might put their identifying numbers on the nameplate along with the motor manufacturer’s catalog and model numbers.

Ensure that the number you use to cross-reference is the motor manufacturer’s model number.

Once you find the number, you can provide it to your supplier or use an online cross-reference tool to find the motor’s direct replacements.

Motor Specifications

Can’t find the motor’s model number? You can match motor specifications instead.

Gathering a few pieces of information, like electrical ratings and physical dimensions, will help you find the right replacement. Make sure to collect as much information as possible and that you record the information correctly. One small error could have you ordering a motor that is completely wrong for the job at hand.

#### Electrical Specifications:

• Horsepower (HP)
• Voltage (V)
• Number of speeds
• RPM – record for each speed if the motor is multispeed
• Single-phase or three-phase
• Service Factor (SF)
• Direction of rotation

#### Physical Specifications:

Frame Size

• If you can’t find this on the nameplate, record the length and diameter of both the motor body and the shaft(s)

Mounting Type:

• Belly band
• Bolt through
• Bracket
• Resilient
• Rigid
• Stud
• Yoke

Enclosure Type:

1. Open air over (OAO)
2. Open drip proof (ODP)
3. Totally enclosed air over (TEAO)
4. Totally enclosed fan cooled (TEFC)
5. Totally enclosed non ventilated (TENV)

Shaft Configuration:

• Single or double shaft

#### Additional Specifications to Look For:

• Will it be mounted in a hazardous location?
• Bearing type
• Motor type:
• PSC
• ECM
• Capacitor start
• Shaded pole

#### Motor Application

• Blower motor
• Fan motor
• Pump motor
• Compressor duty motor
• Draft inducer
• Building exhaust
• Etc.

Once you have collected all of the important information on the old motor, you can provide it to your supplier or use an online cross-reference tool to find the motor’s direct replacements.

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Check out this podcast discussing the operation of a few motors used in the HVAC industry.

Common Cross-Referencing Mistakes to Avoid

When cross-referencing motors, technicians often overlook critical details that can lead to callbacks or equipment damage:

1. Ignoring rotation direction – Installing a motor with the wrong rotation can damage components or reduce system efficiency
2. Mismatching capacitor requirements – PSC motors require specific capacitor ratings that must match for proper operation
3. Overlooking thermal protection – Some applications require motors with internal thermal overload protection
4. Frame size variations – Even motors with the same NEMA frame designation may have different mounting dimensions

For complex motor replacements in heat pump systems, understanding component interactions is crucial. Learn more about how reversing valves work to ensure proper motor selection for heat pump applications.

Summary

Cross-referencing your OEM electric motor isn’t as complicated as some might think. One simple identifying number might be all you need.

And if you can’t find the motor’s model number, all the information you need to find the correct replacement is found right on the motor itself. Taking time to properly document specifications ensures you get the right replacement the first time.

When dealing with advanced control systems, motor replacements may require additional programming or configuration. Understanding BMS control fundamentals can help you navigate motor replacements in building automation systems.

When replacing a belted motor, setting and checking belt tension is a good idea. This video explains how to use a belt tensioning tool.