Goodman Furnace: Flame sensor microamp check
Flame sensor microamp check on a Goodman furnace: Flame current is measured in series with the sensor. The integrated ignition control needs 1 to 4 microamps to prove flame. Contaminated fuel or air can coat the sensor and reduce the signal.
Applies to: Flame sensor and ignition control
Common causes of flame sensor microamp check
- High resistance wiring connections
- Sensor-to-burner gap wrong
- Dirty flame sensor
- Poor grounding
- Failed ignition control (no reading after continuity check)
How to fix flame sensor microamp check: step by step
- Shut off power and disconnect the flame sensor wire from the sensor.
- Connect a micro-amp meter in series between the wire and sensor terminal, positive to the wire and negative to the sensor.
- Restore power and start a heating cycle.
- Read the micro-amp value once flame is established. The hot surface ignitor turns off after proof of flame.
- If the reading is below 1 microamp, check wiring, the sensor-to-burner gap, sensor cleanliness and grounding.
- If there is no reading, check continuity of all components, then replace the ignition control if good.
- Clean a coated sensor with steel wool.
If the unit shows an error code, look it up: Goodman Furnace codes
Source: Goodman GMVC96 service manual, p. 55. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.