Symbio™ 700 Precedent Gas Heat Flame Sensor Troubleshooting
Summary:
This article is to assist in troubleshooting the flame sensor on the White Rodgers ignition board.
Here are some troubleshooting steps to take in the case where the flame is starting, but shutting down after about 30 seconds.
- Visually inspect the flame sensor
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- Sensor should be in the flame
- Ensure that it is not touching any metal
- Check for voltage
- Flame sensor should have about 90 VAC from the end to ground
- If voltage is not present, check for power to the ignition board, harness connection on the board, and wiring to the sensor
- Check the flame signal
- Flame signal can be checked on the flame test port terminals or "Flame TP"
- Set multimeter to µA
- Place meter across the Flame TP
- Nominal flame signal will be 4.5 µA within the 30s after the flame has been established. Flame across the sensor should register at a minimum of 1.2 µA to be considered a valid flame signal.
- Flame signal can be checked on the flame test port terminals or "Flame TP"
Note:
If the flame sensor appears to be working properly and the flame is still not staying on, verify manifold pressure and inlet gas pressures are not dropping. If pressures appear fine, the ignition board may need to be replaced. If there is another similar unit nearby, you can swap the board with it and verify the proper diagnosis.
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.