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Troubleshooting Workflows

Interactive step-by-step diagnostics built for trained HVAC technicians. Each workflow walks through a real troubleshooting sequence — from first symptom to likely repair — with deterministic branching you can follow in the field.

Structured diagnosis matters because guessing burns time and parts. Following a consistent sequence — verify the complaint, confirm power and airflow, then isolate the failed component — keeps you from replacing good parts and missing the real fault. Pair these workflows with our field calculators when a step calls for a measured value.

Start from a Symptom

If you already know the complaint, jump straight in. Each symptom opens a wizard that mirrors how an experienced tech narrows the fault — verifying the obvious first before reaching for gauges or a meter.

Furnace won't start
Pressure switch issue

Inducer runs but system locks out

Burner lights then drops out

Flame proving / sensor failure

Pilot won't stay lit

Intermittent pilot ignition failure

Standing pilot out

Pilot outage, thermocouple, or gas valve

Smart valve issue

Integrated gas valve control failure

Cooling on but weak airflow / warm air

System runs, but output is poor — possible duct or charge issue

Tools:
Static Pressure Budget
Friction Rate
Outdoor unit won't start

No compressor / condenser fan — electrical or control fault

High head pressure

Elevated discharge pressure, hot liquid line

Indoor blower won't run

Motor dead or no signal — electrical / control fault

Tools:
Duct Equivalent
Static Pressure Budget

Heating & Furnace Diagnostics
6 workflows

Ignition, flame proving, pressure switch, and gas valve faults follow predictable sequences. These workflows walk the call for heat through the same checks a service tech runs in the field — power, control board signals, safeties, then the burner. For background on combustion theory, see our HVAC guides.

Flame Sensor Troubleshooting

Step-by-step diagnostic for gas furnace flame-sensing failures — from dirty sensors to grounding and control board faults.

Gas Furnace (standing pilot or hot-surface / spark ignition with flame rectification)

IFC / Spark Ignition Furnace Troubleshooting

Step-by-step diagnostic workflow for gas furnaces with an Integrated Furnace Control (IFC) board and spark ignition. Covers call for heat through normal operation, shutdown sequence, and likely fault identification.

Gas Furnace — IFC / Spark Ignition

Intermittent Pilot Troubleshooting

Step-by-step diagnostic for intermittent pilot ignition systems — from spark failure through flame proving, gas valve operation, and shutdown behavior.

Gas Furnace / Boiler with Intermittent Pilot Ignition (spark-to-pilot)

Pressure Switch Troubleshooting

Step-by-step diagnostic workflow for furnace inducer pressure switch faults — covers tubing, venting, condensate, inducer performance, wiring, and control board interpretation.

Gas Furnace / Induced Draft

Smart Valve / Gas Valve Control Troubleshooting

Step-by-step diagnostic for integrated smart gas valve systems — from call for heat through ignition sequence, flame proving, main burner operation, and shutdown behavior.

Gas Furnace / Boiler with Integrated Smart Gas Valve (e.g., Honeywell SV9500/SV9600, White-Rodgers 36J, Robertshaw 720-400 series)

Standing Pilot Troubleshooting

Step-by-step diagnostic for standing pilot systems — from pilot outage through thermocouple testing, flame quality, gas valve operation, and main burner response.

Gas Furnace / Boiler / Water Heater with Standing Pilot (millivolt or 24V)

Cooling & Airflow Diagnostics
5 workflows

Most "low cooling" calls are airflow problems before they're refrigerant problems. These workflows check filter, blower, and static pressure first, then move into compressor, condenser, and charge diagnostics so you don't connect gauges on a system that just needs a clean coil.

Blower Not Running Troubleshooting

Step-by-step diagnostic for indoor blower motors that won't start, run intermittently, or fail to maintain operation during heating or cooling calls.

Forced-Air HVAC (heating and cooling — PSC or ECM blower)

High Head Pressure Troubleshooting

Diagnose elevated condensing / head pressure on AC and refrigeration systems. Covers condenser airflow, coil condition, fan operation, refrigerant-side causes, and ambient context.

Air-Cooled AC / Heat Pump / Refrigeration

Low Airflow Troubleshooting

Airflow-first diagnostic for weak supply airflow, high Delta T, iced/sweating coils, noisy returns, and room comfort complaints when the blower runs but delivered CFM is low.

Forced-Air / Split / Packaged

Low Cooling Performance Troubleshooting

Diagnose a cooling system that runs but does not meet expected performance — from airflow basics through refrigerant checks.

Split / Packaged Air Conditioning

No Cooling — System Not Running

Diagnose a cooling system that is not starting, not energizing, or where the outdoor unit is completely off.

Split / Packaged Air Conditioning