Mini-Split Diagnostics
The mini-split pages cover ductless systems from three brands. Daikin has a hub with fault-code tables read from two of its US service manuals, each valid only for the indoor and outdoor models that manual lists, and a page for U4, the communication error between the indoor and outdoor units. Fujitsu has a page on how its indoor-unit lamps blink out a code. Mitsubishi Electric has a page on what the symbols and indicator lights on its remote mean.
A mini-split reports trouble as a code on the remote or display, as a lamp blinking in a pattern, or as a symbol you don't recognise, and which of the three you see decides the page to open. Start with your brand, then check that your model is in the document the page cites.
Owner checks stop at reading the code and looking at the outside of the equipment; refrigerant work falls under EPA Section 608.
What is covered
Coverage is per manual, not per brand. A Daikin service manual covers a named list of indoor and outdoor model numbers; a code table read from it is valid for those model numbers and nothing else. Where a family is not in a manual we hold, the page says so instead of presenting a general "Daikin codes" list that would be wrong for half the units it reached.
Start with the brand
Each brand reports faults its own way, so the brand decides which page is useful before the code does. These are the brands GridComfort can read from a manufacturer document:
Indicator lamps and remote symbols
Two brand guides here are about reading the unit rather than a code table: how Fujitsu indoor-unit lamps blink out a fault, and what the symbols and indicator lights on a Mitsubishi Electric remote mean.
Or start with what the unit is doing
A mini-split reports a fault in one of three ways, and which one you are looking at decides where to go next. A two-character code on the remote or the indoor display is the case the brand hubs above cover: find the brand, confirm your model is in the manual's applied-model list, then read the code. A lamp blinking in a pattern is the same information without the characters — Fujitsu splits it across two lamps and Mitsubishi counts blinks on one, and each brand's guide explains its own scheme. A unit that runs but will not heat or cool, with no code and no blinking is not covered here: GridComfort has no mini-split symptom page, and the code tables would not answer it. Sizing questions belong to the BTU calculator instead.