HVAC Sales Master

Fault Code Lookup

HVAC Sales Master
e04
Open Limit (Main Thermal, Rollout Switch, or Reverse Airflow Switch)
This code typically points to
  • Main thermal limit open
  • Rollout switch open
  • Reverse-airflow switch open
Next checks to confirm
  1. Identify which device in the safety chain is open
  2. Check airflow, filter, blower if main limit
  3. Check burners, venting, HX if rollout
  4. Check blower direction/wiring if reverse airflow
Escalation
Heat interrupted by safety opening
Reset behavior
Depends on device; clears when safety circuit restores. Manual-reset devices require manual reset after correction.
Safety Critical
Immediate concern
⚠ Cross-generation conflict
Legacy Code 4 was 'open limit'. The newer S-series e04 includes rollout and reverse-airflow switches in the same code — diagnostic path must branch on which device opened.
Source
Trane 18-CE12D1-1D-EN code-table snippet; same namespace in 18-CE04D1-1D-EN
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