Built for techs who diagnose, not guess
Field-tested troubleshooting, clear explanations, and an AI sidekick that speaks technician—not textbook.
DIAGNOSE. FIX. LEARN. REPEAT.
Real answers. No bullshit.For working HVAC professionalsFIELD TOOL HUB
Jump straight to the tool that gets the call moving.
Free diagnostic demo
Troubleshooting, visual procedures and diagrams
Save calls and reports
10 live worksheets
Source-verified model families
Future plan roadmap
Help improve the field test
START WITH THE SYMPTOM
Practical answers organized around the problems you actually see in the field.
FIELD GUIDE LIBRARY
Troubleshooting, installation and maintenance procedures live together here without cluttering the main navigation.
FREE FIELD TOOLS
Choose the call, work the checks in order, and collect the measurements that actually narrow the problem.
Gas heat
Record the original fault before resetting power. Never bypass a safety or work live unless the manufacturer procedure requires it and you are trained and equipped to do so.
SERVICE CALL WORKBENCH
Capture the equipment and readings once. Save the call on this device or load the details directly into Ask Gauge.
CONNECTED FIELD WORKFLOW
Progress remains on this device and works offline.
This checklist organizes the work; the exact manufacturer procedure, approved instruments, licensing, adopted code and job-specific design always control.
Job: —
Brand: —
Model: —
Refrigerant: —
Fault code: —
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FREE FIELD CALCULATORS
Fast worksheets for common field calculations. Results organize measurements—they do not replace model-specific targets or procedures.
ACTIVE WORKSHEET
Return minus supply in cooling
Temperature split is a screening measurement, not a universal pass/fail target. Compare entering-air conditions, airflow, latent load, and the exact manufacturer data.
MANUFACTURER-SPECIFIC
Choose the equipment type first, then the manufacturer group and exact family. Refrigerant and generation stay with the model—not in a separate section.
Verify blower power and communication wiring, then confirm the motor and control configuration.
Measure ignitor resistance and compare it with the unit specification; inspect the harness and connections.
Measure inducer pressure, inspect venting and combustion air for restriction, and verify pressure-switch operation.
Measure flame-sensor microamps, inspect or clean the sensor, and verify grounding and neutral-to-ground voltage.
Find the cause of the limit trip; check airflow, temperature rise, firing rate, filter, coil, and blower performance.
Inspect for leaks and verify charge using the model-specific procedure; do not add refrigerant from the code alone.
Verify incoming power, connections, and inverter DC-bus conditions using the service-manual flowchart.
Check interconnect wiring, terminals, continuity, power, and boards using the model-family procedure.
Inspect the fan for obstruction, wiring and connectors, motor feedback, and indoor PCB output per the service flowchart.
Inspect compressor sensor circuits, wiring and connectors, then follow the service-manual sensor and outdoor-board checks.
Verify compressor and inverter wiring, winding resistance and insulation, supply voltage, and the position-detection circuit.
Check supply voltage and compressor current, inspect inverter connections, and follow the manual current-sensor diagnosis.
Inspect the outdoor-air sensor placement, connector and harness, then compare resistance with the service temperature table.
Check sensor attachment, connector and harness, then compare thermistor resistance with actual discharge-pipe temperature.
Inspect sensor location and contact, connector and wiring, then test resistance against measured coil temperature.
Inspect outdoor-board cooling, heat-sink condition, ambient exposure, wiring and power components using the manual flowchart.
Verify heat-sink cleanliness and contact, outdoor airflow, fan operation, inverter cooling and compressor load.
Check incoming power, compressor wiring and resistance, heat-sink cooling, operating load, and inverter module per the service flowchart.
Inspect the heat-sink sensor, connector and harness, then compare resistance with the manual temperature table before condemning the board.
Check filter and airflow restrictions, indoor and outdoor fan operation, operating conditions, charge, and refrigerant-circuit restrictions.
Working library · 202 total entries across 12 manufacturer groups · 147 source-verified · 55 held out for source review. Codes are model-family specific; confirm the complete model number and current manufacturer literature before service.
MEMBERSHIP PREVIEW
This is proposed pricing for product planning—not an active checkout. The core field library stays useful without a subscription.
Free
Technician
Pro
Company
Final pricing, question allowances, and company-seat terms will be set after field testing confirms real usage and operating cost.
FIELD TEST
Found something confusing, missing, or flat-out wrong? Send it straight to the team. Contact information is optional.
TRUST & SAFETY
Clear boundaries matter when technicians are working around live voltage, pressure, refrigerant, combustion, and rotating equipment.
The source-reviewed code library, guided diagnostics, field calculators, saved codes, service-call workbench, exports, and printable reports are all available in the current free MVP.
After one successful online visit, the core site, source-verified error codes, guided diagnostics, condensate diagrams, calculators, saved codes, and device-local service calls remain available offline. Ask Gauge, feedback delivery, the private owner dashboard, and external manufacturer manuals still require a connection.
No. Ask Gauge is clearly labeled Free Demo Mode and uses a limited rule-based preview. The protected API connection remains inactive until live AI is deliberately enabled.
They stay in this browser on this device. HVAC Answer Guy does not currently send those notes to a server. Export a backup before clearing browser data or changing devices.
No. Codes are grouped by manufacturer and equipment family. Source-verified entries are shown by default; entries still undergoing source review are clearly separated. Always confirm the full model number and current manufacturer literature.
The site may be read for education, but it does not authorize refrigerant handling. In the United States, anyone performing work that could release regulated refrigerant must meet applicable EPA Section 608 requirements. Users are responsible for certification, licensing, safe work practices, and legal compliance.
No. The site is a field-assistance tool for trained HVAC professionals. It never authorizes bypassing safeties, unsafe live work, or ignoring manufacturer procedures and applicable law.
Feedback is stored privately for product testing. Contact information is optional, and technicians should not include customer names, addresses, passwords, or other private job information.
Field testing, final pricing, user accounts, payment and usage controls, expanded manufacturer coverage, and validation of live AI costs and answer quality.
BUILT FOR THE FIELD
Start with what you see, hear, smell, or measure.
Get targeted checks in the order an experienced tech would run them.
Fix today’s call and sharpen your judgment for the next one.