How to Lubricate the Motor on a Mitsubishi Inverter: A Comprehensive Guide

Maintaining the motor on a Mitsubishi inverter is crucial for its optimal performance and longevity. Proper lubrication is a key aspect of this maintenance, and this comprehensive guide will walk you through the step-by-step process to ensure your Mitsubishi inverter’s motor is well-lubricated and running smoothly.

Identifying the Motor Type

The first step in lubricating the motor on a Mitsubishi inverter is to identify the motor type. According to the Mitsubishi Explosion Proof Motors manual, the motor on your Mitsubishi inverter is likely a squirrel-cage motor. This information is crucial because not all motor types can be lubricated, and using the wrong lubrication method can cause more harm than good.

Locating the Motor

how to lubricate motor on Mitsubishi inverterImage source: Mitsubishi ac By Solomon203

Once you have confirmed the motor type, the next step is to locate the motor within the Mitsubishi inverter unit. If the motor is easily accessible, you can proceed to the next step. However, if the motor is not readily accessible, you may need to disassemble parts of the unit to reach it. Consult the Mitsubishi inverter’s service manual for guidance on the proper disassembly and reassembly procedures.

Inspecting the Motor

Before applying any lubricant, it’s essential to inspect the motor’s bearings for any visible signs of damage or wear. If the bearings are severely damaged, lubrication may not be enough to resolve the issue, and you may need to replace the bearings or the entire motor.

Choosing the Right Lubricant

Selecting the appropriate lubricant is crucial for the proper functioning of the motor. Use a high-quality, non-corrosive lubricant that is specifically designed for the type of motor bearings you have. The lubricant should have the right viscosity to ensure proper lubrication without causing any damage to the bearings or other components.

Here are some recommended lubricants for Mitsubishi inverter motors:

Lubricant Viscosity Recommended for
Mobil Polyrex EM NLGI 2 Mitsubishi squirrel-cage motors
Chevron SRI 2 NLGI 2 Mitsubishi squirrel-cage motors
Castrol Longtime PD 2 NLGI 2 Mitsubishi squirrel-cage motors

Applying the Lubricant

Once you have the appropriate lubricant, use a clean syringe or lubricant dispenser to apply a small amount of lubricant to each bearing. Be careful not to over-lubricate, as this can cause damage or attract dirt and debris, leading to further issues.

When applying the lubricant, follow these guidelines:

  1. Ensure the motor is not running and has had sufficient time to cool down before lubricating.
  2. Apply the lubricant slowly and evenly, distributing it across the entire bearing surface.
  3. Avoid using excessive force or pressure when applying the lubricant, as this can damage the bearings.
  4. Wipe away any excess lubricant that may have been squeezed out of the bearings.

Reassembling the Unit

After lubricating the motor bearings, carefully reassemble the Mitsubishi inverter unit, ensuring that all parts are securely fastened. Follow the manufacturer’s instructions for the proper reassembly procedure to avoid any issues.

Testing the Unit

Once the unit is reassembled, run the Mitsubishi inverter for a short period to ensure that the lubrication has resolved the issue. If the noise or vibration persists, you may need to replace the motor or the bearings.

Advanced Tips

  • Use a digital sound level meter to measure the noise level before and after lubrication. This can help you determine if the lubrication has been effective.
  • If the motor is not accessible or too difficult to disassemble, consider hiring a professional to perform the lubrication.
  • Keep a detailed log of all maintenance activities, including lubrication, to help you track the unit’s performance and identify any potential issues early.


Proper lubrication of the motor on a Mitsubishi inverter is essential for its optimal performance and longevity. By following the steps outlined in this comprehensive guide, you can ensure that your Mitsubishi inverter’s motor is well-lubricated and running smoothly. Remember to always consult the manufacturer’s instructions and use the recommended lubricants to avoid any potential issues.