What It Means
- Communication error between indoor/outdoor INV↔MAIN MICOM (1 min)
Lennox Air handler
Lennox Air handler Error Code 203
Air handler: Air handler (indoor)
Causes & actions from Lennox
How it shows
- Wired controller display: 203
This manual entry does not list further causes or actions.
Applicable models & manual sources
- MMD***M6-1P
Communication error between indoor/outdoor INV↔MAIN MICOM (1 min)
- MMD***S6-1P
Communication error between indoor/outdoor INV↔MAIN MICOM (1 min)
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.
What should you check next?
Continue in ACLogics with guided diagnosis for your equipment and symptoms.
