Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Bryant Furnace 13 Error Code — What It Means
Bryant fault code 13 means the limit device is open — the high-limit switch or rollout switch has tripped and cut gas flow to prevent dangerous overheating. Bryant shares this diagnostic code with Carrier (same parent company, United Technologies). The LED flashes 1 long, 3 short. The high-limit switch monitors heat exchanger temperature; the rollout switch monitors for combustion gases escaping the burner box. Both tripping at the same code means the board can’t distinguish between the two — you need to identify which one tripped. In most cases, restricted airflow causes the high-limit to trip; a cracked heat exchanger or blocked flue causes rollout.
Common Causes
- Dirty air filter — Restricted return airflow is the leading cause of high-limit trips in Bryant residential furnaces. A clogged filter prevents the blower from removing heat from the heat exchanger fast enough.
- Blower motor or capacitor failure — A blower running at reduced speed due to a failing run capacitor doesn’t move enough air and lets the heat exchanger overheat within minutes.
- Rollout switch tripped — If flames are rolling out of the burner box (cracked heat exchanger, blocked flue, or excessive gas pressure), the rollout switch trips. It’s a manual-reset device.
- Blocked supply air distribution — Closed registers, collapsed flex duct, or a blocked supply plenum creates static pressure buildup that starves airflow even with a clean filter.
Step-by-Step Fix
- Check and replace the air filter — Pull and inspect immediately. If it’s grey, clogged, or collapsed, replace it. This clears the majority of code 13 faults.
- Reset the rollout switch — Find the rollout switch (red reset button, mounted near the burner box). Press firmly. If it trips again within one heating cycle, do not operate the furnace — suspect heat exchanger.
- Test blower operation — After a call for heat, blower should start within 60–90 seconds. Test the run capacitor if blower seems sluggish.
- Open all supply and return registers — Walk the space. Open every damper and register. Check for kinked or collapsed flex duct in attic or crawlspace runs.
- Reset the system — Power cycle the furnace and observe 2–3 heating cycles. If code 13 doesn’t return, the airflow fix resolved it.
Parts Often Needed
| Part | Notes |
|---|---|
| High-limit switch | Auto-reset; match temperature rating stamped on old switch |
| Rollout limit switch | Manual-reset; repeated tripping = CO hazard, stop and call a tech |
| Blower run capacitor | Test first; replacing motor without testing capacitor is wasteful |
| Air filter (1-inch or media) | Replace every 90 days |
Need Replacement Parts?
Before ordering, match the furnace part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
A rollout switch that trips repeatedly means combustion gases are leaving the firebox — that’s a CO risk. Don’t operate the furnace. Call a tech to inspect the heat exchanger and flue before the next run.