What It Means
- HIGH PRESSURE SWITCH COMPRESSOR 1
Lennox Unit controller
Lennox Unit controller Error Code 12
Unit controller
Causes & actions from Lennox
How it shows
- M4 alarm code: 12
Compressor is off. Check charge, fans and coil. NOTE: On Ultra-High Efficiency units - if only alarm 12 is present then issue could be high temperature S5 switch. If alarm 12 is accompanied with alarm 14 then most likely it is the high pressure S4 switch. The unit controller will clear high pressure switch alarm when corresponding high pressure switch is detected as closed. Compressor will not restart until corresponding high pressure switch is closed and Minimum Off Delay (cooling or heating) has expired.
Applicable models & manual sources
- MODEL L - M4 UNIT CONTROLLER
HIGH PRESSURE SWITCH COMPRESSOR 1
MODEL L - M4 UNIT CONTROLLER, M4 Unit Controller
Disclaimer: This information is for general reference. Code wording and instructions vary by model. Always follow the service manual for your exact unit.
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