HVACopediaLennox · Air handler
-- Double dashes - zone sensor problem
What the control is telling you
Two dashes shown for indoor temperature on the S30/S40 or zone sensor: loose or miswired connections or two zone sensors on the same zone number. System runs central mode and individual zoning is disabled. S30/S40 thermostat / zone sensor display.
Applies to: Lennox communicating air handlers and EIM-equipped indoor units in S30/S40 smart thermostat systems
Likely causes
- Loose or incorrect zone sensor wiring
- Duplicate zone number
Test and repair steps
- Check zone number assignments.
- Check and correct zone sensor wiring.
- Run the re-configuration procedure.
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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.51. Summarized in our own words; check the original manual for your model.
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