Ductless Mini-Split Troubleshooting: Fault Codes, Frozen Coils, and Communication Errors
Mini-Split Not Working? The Diagnostic Checklist
Blinking LED = fault code. Count the blinks, check the brand service manual. Then:
Frozen coil? Check filter, refrigerant pressure (suction <100 PSI on R-410A = low), outdoor ambient temp, fan motor amp draw.
Communication error? Test comm wire continuity and polarity. Reversed S1/S2 = instant comm fault. Mitsubishi: outdoor is the master. LG: indoor drives comm.
No cooling, no fault? Connect manifold gauges. Suction pressure tells you most of what you need to know.
Drain dripping? Vacuum exterior drain outlet + condensate tablet in drain pan.
Full guide at ServiceMag












