Fault Code Lookup

HVAC Sales Master
LED #1 fast flash / LED #2 slow flash
Reversed line polarity
This code typically points to
  • Line hot-neutral reversed at incoming power

Next checks to confirm
  1. Verify incoming polarity with meter
  2. Correct line wiring

Escalation
Control will not operate normally
Reset behavior
Clears after wiring corrected.
Urgent
Fix now
Source
Lennox ML180UH heating sequence, p.40; G61MPV code table p.63