Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Trane XR80 Error Codes — What They Mean
The Trane XR80 is a single-stage 80% AFUE gas furnace that communicates faults through a status LED located behind the lower access door. The LED blinks a sequence of long and short flashes to indicate the fault code. Count the flashes, pause, then count again to confirm the code. A steady ON light means the furnace is operating normally. A steady OFF light with no power to the board is a separate power supply issue.
Trane XR80 Flash Code Reference
| Flash Code | Meaning | Priority |
|---|---|---|
| Steady ON | Normal operation | — |
| 1 Flash | System lockout (exceeded retry/recycle count) | High |
| 2 Flashes | Pressure switch stuck open | Medium |
| 3 Flashes | Pressure switch stuck closed | Medium |
| 4 Flashes | Open high-limit device | High |
| 5 Flashes | Flame sensed without call for heat | High |
| 6 Flashes | 115V AC power reversed (polarity fault) | Medium |
| 7 Flashes | Gas valve circuit fault or low flame signal | High |
| 8 Flashes | Low flame signal / ignition problem | High |
| 9 Flashes | Blower on-delay timeout (blower not starting) | High |
Step-by-Step Fix
Code 1 — System Lockout: Reset the furnace by cutting power at the disconnect for 30 seconds. If it relocks immediately, the underlying fault (pressure switch, flame sensor, or gas) needs to be resolved first.
Code 2 — Pressure Switch Stuck Open: Check flue/intake pipes for blockage. Inspect pressure switch hose for cracks or condensate. Test pressure switch continuity with the inducer running — it should close.
Code 3 — Pressure Switch Stuck Closed: Switch contacts are welded closed or there’s a wiring short. Replace the pressure switch.
Code 4 — High Limit Open: Check air filter (replace if dirty), confirm all registers are open, test blower operation (run capacitor). If limit trips with adequate airflow, suspect a cracked heat exchanger.
Code 5 — Flame Without Call: Gas valve is leaking or the flame sensor wire has a short to ground. Turn off the gas and call a technician.
Code 6 — Polarity Fault: Check the 115V AC wiring to the furnace. The hot and neutral wires may be reversed at the disconnect or outlet. Correct polarity and reset.
Code 7 — Gas Valve or Low Flame: Check gas supply pressure, clean the flame sensor, inspect the gas valve wiring. Replace gas valve if supply pressure is confirmed normal.
Code 8 — Low Flame / Ignition: Clean the flame sensor rod with steel wool. Check ignitor resistance (40–100 Ω cold for silicon carbide). Verify manifold gas pressure.
Code 9 — Blower Timeout: Test the run capacitor (match µF rating). Check for debris binding the blower wheel. Verify 120V at the motor.
Parts Often Needed
| Part | Notes |
|---|---|
| Flame sensor rod | Most codes 7 and 8 start with the sensor |
| Blower run capacitor | Code 9; match µF and voltage on the capacitor label |
| Hot surface ignitor | Code 8; silicon carbide, 120V |
| Draft pressure switch | Codes 2 and 3 |
| High-limit switch | Code 4; match temperature rating |
Technician Tips
Trane furnaces typically flash error codes through the LED on the integrated furnace control (IFC) board. Code 11 (no previous code) is the startup default — if you see this with a no-heat call, check for power at the IFC. Code 12 means blower on after power-up — normal after a reset. Code 13 means limit switch fault — this is often a dirty filter or restricted return. Code 14 means ignition failure — check gas pressure before condemning the igniter. Trane uses silicon nitride igniters that last longer than standard carbides but are more fragile during handling.
Estimated repair time: Most Trane ignition faults take 30-45 minutes to diagnose and fix. Limit switch and blower motor issues run 1-2 hours.
Need Replacement Parts?
Before ordering, match the HVAC 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
Code 5 (flame without call) is a gas leak/valve failure — shut off the gas and do not attempt DIY repair. Code 4 that recurs after replacing the filter and confirming airflow may indicate a cracked heat exchanger, which requires professional inspection and is a carbon monoxide hazard.