What It Means
- GAS CAB NO OPEN PROOF GV1
Lennox Unit controller
Lennox Error Code 166
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 166
This alarm will occur when the combustion air pressure switch (S18) is detected as closed immediately after the furnace demand relay is energized and before the combustion air blower is energized. Gas valve 1.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
GAS CAB NO OPEN PROOF GV1
MODEL L - M4 UNIT CONTROLLER, M4 Unit Controller
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.
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