Diagnosis
How to ask ACLogics for the fastest, most accurate diagnosis
What to provide and in what order — equipment and error code, symptom description, and what to do when there is no error code at all — to get the sharpest possible diagnostic workflow.
ACLogics narrows a diagnosis in stages: equipment first, then the error code if there is one, then the symptom. Each stage removes possibilities the next stage can’t. Giving them in this order, with as much precision as you have, is what gets you to the right answer fastest — but none of them are hard requirements. If something isn’t available, skip it and keep going.
1. Equipment and error code come first
Start with the model, and the error code if the unit is showing one. This is where our database does the most work: the same brand can behave very differently across production years and generations, so the exact model number matters more than the brand alone. Two units from the same manufacturer, a few years apart, can use a completely different fault-code scheme on the same-looking board.
If you can get the code straight off the control board or backplate rather than just counting blinks on an LED, that’s the most precise source — boards often expose a numeric or alphanumeric code with more resolution than the flash pattern alone. Use Nameplate Scan to capture brand, model, serial, and manufacture date in one photo instead of typing it in.
[!TIP] If the board is hard to access, the label is worn, or the code is genuinely unclear — that’s fine. Enter what you can read, or skip it entirely. ACLogics falls back on its equipment database and diagnostic experience to reason through the rest; it does not need a perfect code to start.
2. Describe the symptom precisely — this is what rules candidates out
An error code narrows the field, but it rarely points to one single cause. Most codes still map to several plausible failures. The symptom description is what tells ACLogics which of those remaining candidates actually fits what you’re seeing in front of you.
The more specific and unusual the detail, the more it rules out. Vague phrasing like “it’s not cooling” leaves every candidate on the table. Give it something concrete to eliminate with:
- Temperature — indoor and outdoor ambient, supply/return, or line temperatures.
- Timing — seconds vs. minutes matters; when exactly in the cycle something happens or stops.
- Delta-T — the difference between two readings, not just one number in isolation.
- Sequence — what happened first, second, third, in the unit’s own cycle.
For the full breakdown of what a strong symptom description looks like — including a vague-vs-pro-level cheat sheet — see Write a better symptom.
3. No error code at all? That’s still enough to start.
Plenty of equipment doesn’t surface a fault code — older units, some mini-splits, or systems where the board just isn’t communicating one. That doesn’t block a diagnosis. Provide whatever you do have (equipment info, symptom, readings) and ACLogics guides you through the next check step by step from there, the same way a lead tech would talk you through it over the radio without a code to start from.
See Start a new diagnosis for the full intake flow, including where to tap “I don’t have an error code” to skip straight to the symptom step.
Quick reference
| You have | What to do |
|---|---|
| Model number + clear error code | Enter both — this is the fastest path to a narrow answer. |
| Model number, code is a guess or hard to read | Enter what you can read, or skip the code and move to the symptom. |
| No error code at all | Skip it. Describe the symptom with as much detail as you can. |
| A unique or unusual symptom detail | Include it — it’s often what separates two otherwise-identical-looking causes. |
Need support?
Email ACLogics with the issue details.
Include the account email, device model, app version if known, screenshots, and the exact message shown.