When it comes to maintaining your Lennox HVAC system, testing the fan motor is a crucial step to ensure its proper functioning. This comprehensive guide will walk you through the step-by-step process of testing a Lennox fan motor, providing you with the technical expertise and hands-on approach to diagnose and troubleshoot any issues.
Checking the Voltage
The first step in testing a Lennox fan motor is to check the voltage. This is a crucial step as it helps you determine if the motor is receiving the correct power supply. To do this, you will need a multimeter.
- Set your multimeter to the AC voltage setting.
- Locate the motor terminals and touch the probes of the multimeter to them.
- For a 120-volt motor, you should see a reading between 110 and 120 volts. If it’s a 240-volt motor, the reading should be between 220 and 240 volts.
- If the voltage reading is significantly lower or higher than the expected range, it could indicate a problem with the power supply or the motor itself.
Checking the Continuity
Image source: Lennox Ac by Raysonho
Next, you’ll need to check the continuity of the motor. This will help you determine if the motor windings are intact and functioning correctly.
- Disconnect the motor from the power source.
- Set your multimeter to the ohms (Ω) setting.
- Touch the probes of the multimeter to the motor terminals.
- You should see a low resistance reading, typically between 1 and 5 ohms.
- If the reading is significantly higher or if you don’t get a reading at all, it could indicate a problem with the motor windings.
Checking the Windings
To further investigate the motor windings, you’ll need to check the AC voltage across the windings.
- Set your multimeter to the AC voltage setting.
- Touch the probes of the multimeter to the motor terminals.
- You should see a voltage reading, which will vary depending on the motor’s design and specifications.
- If you don’t see a voltage reading, it could indicate an open or shorted winding, which would require the motor to be replaced.
Checking the Capacitor(s)
If the Lennox fan motor has a capacitor(s), you’ll need to test it as well.
- Set your multimeter to the ohms (Ω) setting.
- Touch the probes of the multimeter to the capacitor leads.
- You should see a very high resistance reading, typically in the range of several thousand ohms.
- If the reading is significantly lower or if you don’t get a reading at all, it could indicate a faulty capacitor that needs to be replaced.
Checking the Centrifugal Switch
Some Lennox fan motors have a centrifugal switch that helps control the motor’s operation. You’ll need to test this switch as well.
- Set your multimeter to the ohms (Ω) setting.
- Touch the probes of the multimeter to the switch terminals.
- You should see a very high resistance reading when the switch is open and a low resistance reading when the switch is closed.
- If the switch is not functioning correctly, it may need to be replaced.
By following these steps, you’ll be able to thoroughly test the Lennox fan motor and identify any potential issues. Remember to always prioritize safety and consult a professional if you’re unsure about any aspect of the testing process.
Reference:
1. Furnace Blower Motor Voltage Testing – YouTube
2. How to check if a lennox blower motor is bad – YouTube
3. Lennox condenser fan – HVAC-Talk