What's the system doing?

Pick the equipment, tap the fault. I'll walk it with you like a senior tech on the truck.

Professional-use reference — confirm consequential decisions with the exact unit's OEM literature, measurements, and applicable requirements.

Common calls

PREVIEW

Toolbox PRO

$29/mo · free during beta

🔒Model-specific AI — answers grounded on the OEM service manual for the exact unit in front of you
🔒Rating-plate scan — photo the nameplate, get model, tonnage, charge & fault-code legend instantly
🔒Job reports — branded PDF of readings + diagnosis to attach to the invoice
🔒Logbook & history — every diagnosis saved per customer/unit

Fault code lookup

Public release: verified fault-code records only. A bare code is never one authoritative answer: resolve the manufacturer, family, model, and control context before relying on a match.

Field tools

Component encyclopedia

PT chart

📊 Pressure–Temperature chart

Saturation pressures · psig · 5°F steps

Reference-grade data for field triage — verify critical charging decisions against the OEM PT card on the equipment. High-glide blends (R-407C): use dew for superheat, bubble for subcooling, charge liquid-only.

Refrigerant reference — A to Z

PUBLIC BETA — independent trade & legal review in progress · review status & corrections
Professional-use reference. OEM literature, instrument readings, applicable codes, and qualified technician judgment govern. Do not bypass safety devices. Refrigerant work may require EPA Section 608 certification.
Review status & correctionsSources & methodology Safety disclaimer Privacy Terms
TOOLBOXHVAC v0.8.11 · DATA PACK 2026-08-06-N · GUIDED DIAGNOSTICS (PRE-AI) · REFERENCE DATA — VERIFY WITH METERS & OEM DOCS