How to Test Daikin Fan Motor: A Comprehensive Guide

Troubleshooting a malfunctioning Daikin fan motor can be a daunting task, but with the right approach and tools, you can diagnose and resolve the issue efficiently. This comprehensive guide will walk you through the step-by-step process of testing a Daikin fan motor, providing you with the technical details and expert insights to ensure a successful DIY repair.

Preparing for the Test

  1. Turn off Power and Wait: Before beginning the testing process, it is crucial to turn off the power to the unit and wait for at least 10 minutes. This ensures that any residual voltage in the system is fully drained, preventing potential electrical hazards.

  2. Isolate the Motor: Locate the motor plug on the printed circuit board (PCB) and disconnect it. On Douglas units, the plug is typically labeled as S70 or S71, depending on the model. For Live Sky air and VRV systems, the plug is usually labeled as X106a and X107a.

Testing the Resistance

how to test daikin fan motorImage source: Daikin Air Conditioner Outdoor by Dinkun Chen

  1. Measure Resistance: Using a multimeter, measure the resistance between the different wires on the motor plug. Your negative lead should be placed on the blue wire. Ensure that your meter leads are properly connected to the correct spots on the plug.

a. Blue to Red and Blue to Orange: The resistance reading should be 100 kΩ (100,000 ohms) or higher.
b. Blue to Brown: The resistance reading should be 100 Ω (100 ohms) or higher.
c. Blue to White: The resistance reading should be 1 MΩ (1,000,000 ohms) or higher.

All resistance readings should be less than infinity, indicating a functional motor winding.

Checking Voltage Outputs

  1. Measure DC Voltage: With the power applied to the condenser, set your multimeter to measure DC Volts. Place the negative lead on pin 4, where the blue wire on the plug connects to the PCB. Place the positive lead on pin 7, where the red wire connects to the PCB. The expected voltage reading should be between 310 VDC and 340 VDC. If the voltage is not present, the PCB is likely defective.

  2. Verify 5 VDC: Keep the negative lead on pin 4, where the blue wire connects to the PCB. Move the positive lead to pin 3, where the brown wire connects to the PCB. You should measure a reading of 5 VDC. If this voltage is not present, the PCB is considered defective.

Additional Tips and Insights

  • The service manual may instruct you to check the resistance between the leads, but the small size of the plug can make it challenging to do so directly. You can still measure the resistance by disconnecting the plug from the board and using a multimeter to measure the resistance between the leads.
  • When testing the fan motor, ensure that you use micro leads for your multimeter to accurately measure the resistance and voltage.
  • If you are unable to obtain any resistance readings between the wires or to earth on either fan, there may be an issue in the indoor unit. In this case, you can try to isolate the fan by checking the resistance between the wires and earth.

By following these detailed steps and utilizing the technical insights provided, you can effectively test and diagnose the Daikin fan motor, empowering you to tackle this DIY repair with confidence.

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