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.

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The Three-Step Workflow

01

Describe the Lockout Pattern

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

02

Run Ordered Tests

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

03

Apply the Fix With Evidence

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

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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.

Simple, Transparent Pricing

Built for independent experts.

Solo Plan

$15 /month

Billing: Perfect for trying it out with a small client base

  • AI-Powered Rapid Troubleshooting
  • 90-day searchable history
  • Professional PDF reports
  • Zero-Signal Offline Mode
  • 500K tokens per month

Strategic oversight & operations.

Insight Plan

$89 /month /technician

Billing: For leadership and owners

  • Everything in Team Plan
  • On-Demand Master Tech Consultation
  • Enterprise Operations Command Center
  • Operational trend reporting
  • Custom API & Workflow Integration
  • 4M tokens per month

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.