HVAC Field Manual

A phone- and iPad-ready residential HVAC service system that guides a complete diagnostic or maintenance visit, keeps airflow and equipment context attached to every reading, preserves field evidence, and freezes a trustworthy permanent report.

Ten guided stepsContinuous autosaveField photo evidencePrivate by default

HVAC FIELD MANUALFIELD READY

GUIDED CALL · STEP 09 / 10Diagnostic reviewAirflow confirmed · readings autosaved

LOW SIDE124PSIG

HIGH SIDE355PSIG

REFRIGERANT: R-410A
SUBCOOL: 10.0°F
DELTA T: 18.4°F

6 diagnosticsPhotos categorizedReady to freeze

The field problem

A good diagnosis needs the whole service call—not one isolated number.

Residential HVAC work combines safety, airflow, electrical measurements, refrigeration readings, equipment baselines, coil and filter condition, photos, and technician judgment. This system keeps that context together and deliberately blocks refrigerant-pressure entry until airflow has been confirmed, reducing the chance that an airflow problem gets mistaken for a charge problem.

Guided service call

Ten steps, ordered by field conditions.

A draft is created immediately and autosaves throughout the visit. The workflow moves from safety and equipment condition into electrical checks, airflow, and finally refrigeration data so later conclusions have the context they need.

01SetupCall type · complaint · safety
02Inspect / cleanCondenser condition · cleaning decision
03ElectricalLine voltage · compressor amps · fan amps
04CapacitorsCompressor / HERM · fan · tolerance
05OutdoorAmbient dry-bulb · observations
06IndoorFilter · coil · blower · drain · wet-bulb
07AirflowReturn · supply · delta-T · confirmation
08RefrigerationPressures · line temps · SH / SC
09ReviewDiagnostics · targets · decision paths
10FinishWork · follow-up · freeze

DIAGNOSTIC REVIEWCONTEXT VERIFIED

DELTA-TNormalSupply vs return

SUPERHEATReviewFixed-orifice target

SUBCOOLINGNormalTXV target ± tolerance

COMPRESSOR% of RLAUtilization indicator

CONDENSER FAN% of FLANameplate comparison

CAPACITOROut of rangeRated vs measured

Illustrative classifications only. Customer equipment readings remain inside the private application.

Diagnostics with guardrails

Measurements become useful only after the context is verified.

The application calculates and classifies the readings that matter while preserving the technician’s observations. Charging guidance changes with the metering device: TXV workflows emphasize subcooling, while fixed-orifice systems expose a superheat target based on the available indoor and outdoor conditions.

Indoor dry-bulb and wet-bulb, outdoor ambient, return air, and supply air stay with the refrigeration dataset
Low/high-side pressure, saturation temperatures, suction/liquid-line temperatures, superheat, and subcooling are captured together
Dual-run capacitor checks store compressor/HERM and fan rated versus measured µF independently, using the component’s printed tolerance
Target provenance is preserved: manufacturer chart, unit sticker, indoor-WB/outdoor-DB chart, prior verified baseline, app calculation, or technician judgment
Normal, caution, and out-of-range states provide troubleshooting context without replacing technician judgment

Evidence, not memory

Every completed record keeps the reason behind the repair.

Photos are captured by category instead of dropped into one camera roll. The final checkpoint identifies missing fields, records a reason for each intentional omission, and captures whether follow-up work is needed. A visit can therefore preserve a focused electrical, airflow, refrigeration, or inspection dataset without pretending every maintenance action was performed.

Equipment labelWiring diagramCapacitor label Before cleaningAfter cleaningAirflow evidence Refrigerant connectionIndoor / outdoorHandoff evidence

REPORTS LIBRARYService history

FILTERED VIEW

EquipmentDateService typeDiagnosticsFollow-up

#0042 · Cooling maintenanceCompleteEvidence + frozen equipment snapshot

#0043 · Diagnostic callDraftAutosaved · completion tracked

Permanent service record

Save, freeze, and preserve what was true that day.

Completion freezes the diagnostic output and equipment snapshot so later profile changes cannot rewrite history. Reports remain searchable by equipment, date, service type, completion, abnormal diagnostics, and follow-up state. That history also creates the foundation for comparing future readings against prior verified baselines instead of judging every service call as an isolated snapshot.

Deployment

Field-ready on the LAN. Operational data stays private.

Laravel 13 runs in a Docker Compose stack with Nginx, PHP, MariaDB, and persistent photo storage on Raspberry Pi hardware. SQLite and MariaDB test suites protect both development and production database paths.

Phone / iPad→Private LAN→Nginx + Laravel→MariaDB + photos→Raspberry Pi

My role

Product design, application engineering, field testing, and technical writing.

I translated an actual residential HVAC service call into a guarded application workflow, built the data model and diagnostics, designed the tablet and phone experience, and added regression coverage for SQLite, MariaDB, completed-record immutability, validation, photos, reporting, and Docker deployment.