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Error code reference
Lennox Furnace Error Code 4 Flashes
Primary limit switch open (Control 103085).
SourceLennox ML195DF Series - Service Manual: High-Efficiency Gas FurnacesPage 9, Table 6
Diagnostic procedure
The full 4 Flashes procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Check for restricted airflow, dirty filter, or failed limit switch.
SourceLennox ML195DF Series - Service Manual: High-Efficiency Gas FurnacesPage 9, Table 6
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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Where this code is documented
4 manuals in the MyPros+ library document this code for Lennox furnace.
Models covered by the manuals that document this code
- ML180DF045P24A
- ML180DF045P36A
- ML180DF070P36A
- ML180DF070XP36A
- ML180DF090P36B
- ML180DF090P48B
- ML180DF090XP48B
- ML180DF110P60C
- ML180DF110XP60C
- ML193UH
- ML193UH045P36B
- ML193UH070P24B
- ML193UH070P36B
- ML193UH090P36C
- ML193UH090P48C
- ML193UH110P48C
- ML193UH110P60
- ML195DF
- ML195DF045XP36B
- ML195DF070XP36B
- ML195DF090XP60C
- ML195DF110XP60C
- ML195UH
- ML195UH045XP24B
More models are covered than are listed here.
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