Ductless
Mini-Split Diagnostic
Mini-split throwing errors or not cooling? Six Star's ductless diagnostic checks thermistors, flare joints, charge, comm, and drain — the actual fail points.
When Your Mini-Split Isn't Working Right
Ductless mini-splits are more sensitive to install quality than any other residential HVAC equipment — a small refrigerant leak at a flare joint, a partially blocked drain, or a bad indoor thermistor will throw error codes and shut the system down. Our ductless diagnostic finds the real fault before we quote parts.
What Our Ductless Diagnostic Actually Checks
Error code interpretation and history. Every major mini-split brand (Mitsubishi, Fujitsu, Daikin, LG) has its own error code system. We pull the current code and (where the equipment supports it) the fault history — the pattern of past faults often points to the real root cause faster than the current symptom.
Indoor head sensors and thermistors. Room air, coil, and discharge thermistors are the "eyes" of a mini-split's control board. A drifted thermistor will cause miscommunication faults, staging problems, or a system that runs but never satisfies. We measure resistance against manufacturer specs at ambient temperature.
Line-set flare joints and refrigerant charge. Most refrigerant leaks on ductless systems are at the flare fittings — improper torque, over-flared, or damaged during install. We leak-check flares with electronic detector or bubble solution, and verify charge by weight or superheat depending on the equipment.
Condenser communication with indoor head(s). Multi-zone systems use serial communication between the outdoor and each indoor. A comm fault often looks like an "indoor unit not responding" error but is actually wiring, polarity, or a bad board. We check both ends.
Drain pan, drain pump, and slope. Indoor heads sit above finished ceilings — a plugged drain is a water damage problem, not just a comfort problem. We check the drain pan cleanliness, pump function (on systems with pumps), and slope of the drain line to the exterior.
What You Get
A clear explanation of which component failed, whether it's under warranty (most manufacturers cover 5-10 years on parts), and honest repair-vs-replace guidance. Book a ductless diagnostic today.
Ready When You Are
Schedule service or ask a question — a real person at Six Star is standing by.