HVAC Fault Code Diagnosis, Before the Truck Rolls
Know before you go. Diagvance turns the model, control board and fault code from a service call into ranked likely causes and the next factory test. Your technician knows what to check and what to bring, before arrival.
PRE ARRIVAL BRIEF · SAMPLE
Fault code
Ignition lockout
Likely cause
Flame sensor
Brief
SENT
◎
Online Intake
Model, board and fault code at booking
✦
Factory Based Diagnosis
Ranked likely causes, from factory documentation
▣
Dispatcher Alert
Right technician, likely part on the truck
⚡
Technician Brief
The next factory test, before arrival
WHAT YOU GET
From the Service Call
to the Right First Visit
One workflow that prepares your dispatcher and your technician before the truck leaves, using factory documentation for the exact equipment.
Factory Documentation First
Fault codes and test procedures taken from official manufacturer documentation.
Field Experience
Checked against years of hands-on service work and technician knowledge.
Ranked Likely Causes
The most probable faults first, each with its factory test.
Right Part, Right Technician
Dispatch with the likely part loaded and the right skill level assigned.
How We Use AI
AI Matches the Fault to Factory Data, It Does Not Guess
Our AI has one job. It reads the fault information from the system and matches it to the right record in our diagnostic database. The diagnosis comes from that record, not from the AI.
Writing the Answer
The AI does not invent a diagnosis from general knowledge.
Its Own Analysis and Calculation
The AI does not decide what is wrong by running its own analysis.
Extraction and Matching
The AI extracts the fault details and matches them to our database.
The Diagnostic Database
What Our HVAC Diagnostic Database Is Built From
Diagvance is not built around a single AI model or a set of generic troubleshooting answers. The work starts with the data. These five layers are in place, and the diagnostic engine is now being tested against real service cases.
Furnace Diagnostic Records
Furnace fault codes, model families, control boards and diagnostic sequences, including older systems, across major North American manufacturers.
HVAC Technicians
Field knowledge that captures how experienced technicians reason through a fault, including the details that manuals leave out.
Real Service Cases
Customer complaints, equipment details, technician findings, measurements, repairs and final outcomes, used to study how diagnostic decisions are made.
Usage and Failure Patterns
Frequently replaced components and recurring failures add context and help service teams prepare before arrival.
Thermostat, Sensor and Field Data
We are testing which inputs actually improve diagnosis: thermostat data, temperature, electrical readings, pressure, airflow and other field measurements.
Who It Is For
Built for HVAC Service Businesses With 1 to 15 Technicians
Owner operators working alone are welcome. The owner or service manager buys it. Dispatchers and technicians use it every day.
Owners and Service Managers
Fewer return visits, the right part on the truck, and consistent diagnosis across senior and junior technicians.
Dispatchers and Technicians
The dispatcher sees the likely cause before assigning the call. The technician reads the brief before arrival.
Homeowners
The homeowner or the office gives the model, the fault code and the symptoms at booking. Homeowners are not the buyer.
LATEST RESEARCH
What the Research Says About
HVAC Fault Diagnosis
Plain-language briefs on published field studies about fault detection, remote monitoring and heat pump performance, with links to every original source.
What Remote Monitoring Revealed About Cold-Climate Heat Pumps
Field studies that logged heat pumps minute by minute found identical models performing very differently, mostly because of installation and settings rather than the…
Read article →
Can Smart Thermostat Data Detect a Refrigerant Problem?
Oak Ridge National Laboratory tested how much remote data can reveal about refrigerant charge. Large undercharge showed up clearly. Small undercharge, the kind…
Read article →
Installation Faults Can Add Up to 40% to HVAC Energy Use
A 2026 field study of 83 recently installed residential systems found that most had at least one installation fault. Combined faults raised cooling energy by up to 40%…
Read article →PILOT SCORECARD
Measured on Real Calls,
Not Promised
In a pilot, every brief is timestamped before the visit and compared with what the technician actually found. You see the numbers for your own shop.
Eligible Calls
30 to 50
Top 3 Causes
Scored
Next Test
Scored
Return Visits
Tracked
Scorecard layout only. Results are published after real pilots.
ABOUT DIAGVANCE
Built by a Technician,
Grounded in Factory Documentation
Diagvance is built by an HVAC service technician with more than 9 years in the field. The diagnostic database starts from official manufacturer fault codes and procedures, then adds what technicians learn on real calls and what parts are actually replaced.
5
Steps, from call to brief
9+
Years of field experience
BC
Built in Vancouver, Canada
Customer Data Security
Your Customer Data Stays Yours
We take customer data seriously. The diagnosis runs on technical details, and your customer list is never the product.
Technical Details Only
Model, control board, fault code and readings. Names, phone numbers and addresses are not sent to the AI.
No AI Training
Customer data is not used to train public AI models.
Never Sold
We do not sell or share customer data with advertisers or data brokers.
Your Control
Ask what we hold, correct it, or have it deleted at any time.
Questions
HVAC Diagnostic Software, Plain Answers
What is Diagvance?
A workflow for HVAC service companies that turns the model, control board and fault code from a service call into likely causes and the next factory test, before the technician arrives.
Does it replace the technician?
No. It prepares the technician. The final diagnosis and the repair always stay with a qualified technician on site.
Do I need an app or hardware?
No. It runs through an online form, text and email. There is nothing to install and no hardware to buy.
What does it need to work?
The equipment model, the control board and the fault code, plus the symptoms the customer describes.
What does it cost?
The pilot is free for 3 design partners. After the pilot, a subscription priced by the number of briefs per month.
Is my customer data safe?
Names, phone numbers and addresses are not sent to the AI, and customer data is never sold or used to train public AI models.
PILOT PROGRAM
Become a Pilot
Design Partner
We are selecting 3 HVAC service companies for a free shadow mode pilot. Nothing changes in your workflow. Get in touch to apply or to see a demo.
Apply or Book a Demo →© 2026 Diagvance | Data Security | Pilot | Pricing | Contact