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info Honeywell
Status AC LED On, DC LED On
Normal operating conditions — the enclosure power supply is functioning properly with both AC and DC power available.
? What Causes This
Normal operation.
ⓘ What This Means
No action required. System is operating normally.
Source: page 2 of the official manual
From the manual
This error code appears in:
Honeywell Pro 5000 Thermostat