How to check flame sensor current

FAQ | Apr 08,2023

Checking the current of a flame sensor typically involves using a multimeter to measure the electrical current flowing through the sensor. Here are the steps to follow:

  1. Turn off power: Before starting, turn off power to the furnace or heating equipment to avoid the risk of electric shock.
  2. Locate the flame sensor: The flame sensor is typically located near the burner assembly of the furnace. Consult the furnace manual or manufacturer’s website to locate the sensor.
  3. Disconnect the sensor: Disconnect the flame sensor from the furnace control board. This may involve unplugging a connector or removing a wire.
  4. Set the multimeter: Set the multimeter to measure DC current in the appropriate range. Consult the multimeter manual if you are unsure of the proper setting.
  5. Connect the multimeter: Connect the multimeter leads to the two terminals on the flame sensor. Be sure to observe the correct polarity.
  6. Power on and test: Turn the power back on and observe the multimeter reading. The typical reading for a flame sensor is in the range of 1.5 to 4 microamps. If the reading is outside this range, the sensor may be faulty and should be replaced.

Note: If you are not comfortable with performing these steps or are unsure of your abilities, it is recommended to contact a licensed HVAC technician to check the flame sensor.

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