System Diagnostics

Furnace Troubleshooting for Normal but Tricky Failures

From short cycling to late-stage lockouts, ACLogics guides your team through sequencing, measurement, and confirmation so fixes stick.

Download on the App Store

ACTIVE_SCAN_MODE

ANALYZING_SYSTEM_DATA...

> DIAGNOSIS_READY

> CONFIDENCE: 98.4%

> VIEW_STEPS_BELOW

The Three-Step Workflow

Describe the Lockout Pattern

Enter exactly when the failure occurs: during ignition, after flame prove, or after several minutes of run time.

Run Ordered Tests

The assistant prioritizes checks that separate control faults from venting, gas delivery, and airflow faults.

Apply the Fix With Evidence

Get a root-cause summary and a report that documents readings, decisions, and final verification.

Download on the App Store

Built for Precision

Everything you need to diagnose with confidence and accuracy.

Ignition Sequence Mapping

Validate each stage from inducer call to flame prove, so missed transitions and intermittent breaks are visible.

Safety Circuit Clarity

Pinpoint pressure switch, rollout, and high-limit behavior with guided voltage and continuity checks.

Airflow-Driven Limit Analysis

Correlate temperature rise and blower performance to find why limits trip under real operating load.

Deployment

Simple, Transparent Pricing

This page stays focused on the system workflow first. Compare plans separately when you want to deploy ACLogics across more calls and more technicians.

Free Plan

$0 /month

Explore the core workflow at no cost.

Solo Plan

$15 /month

Built for independent experts.

Team Plan

$25 /month /technician

Standard for growing HVAC shops.

Compare plans

Frequently Asked Questions

Burners light, then drop out in 3-5 seconds, even after cleaning the flame sensor. What is next?

Check furnace grounding and neutral integrity. Poor ground return can mimic a bad flame sensor by distorting microamp signal to the board.

Limit code appears only after the blower door is installed. Why would that happen?

Door position can change return-air behavior. Recheck filter loading, blower speed tap, and static pressure with the system fully closed.

Inducer starts but pressure switch closes only sometimes. Is the switch itself bad?

Not always. Inspect condensate trap routing, vent termination, and collector box port restrictions before replacing the switch.

Can I jump a limit or pressure switch just to keep the call moving?

No. Bypassing safeties creates risk and hides the true fault. Use controlled diagnostic measurements instead of defeating protection devices.

Ready to Diagnose Faster?

Get the precise sequence and support you need on every call.

Download on the App Store