Run capacitor
Common no-start and weak-compressor failure point. Match the microfarad and voltage rating.
Trane XR13 Air Conditioner Error Codes — What They Mean
The Trane XR13 is a 13 SEER single-stage central air conditioner in Trane’s value-line residential series. It uses R-410A refrigerant and a single-speed scroll compressor. Like most entry-level condensing units, the XR13 relies on a diagnostic LED on the control board to report faults via flash sequences rather than communicating through a smart thermostat. The LED is visible through the access panel on the outdoor unit.
Trane XR13 LED Flash Code Reference
| Flash Sequence | Fault |
|---|---|
| Continuous ON | Normal operation |
| 2 flashes | High-pressure switch open |
| 3 flashes | Low-pressure switch open |
| 4 flashes | Open circuit — compressor protection device |
| 5 flashes | Control board fault |
| 6 flashes | Outdoor thermistor fault |
| 7 flashes | Loss of charge (pressure switch) |
| 8 flashes | Anti-short cycle delay active |
| 9 flashes | Communication fault (if connected to ComfortLink thermostat) |
Common Causes by Code
- 2 flashes — High pressure — Restricted condenser coil, failed condenser fan motor, or refrigerant overcharge. The XR13 does not have an inverter-driven fan — if the capacitor fails, the fan stops and high-pressure faults follow within minutes.
- 3 flashes — Low pressure — Refrigerant leak or low ambient temperature. The XR13 has no factory low-ambient kit and will trip the low-pressure switch below about 45°F outdoor temperature.
- 4 flashes — Compressor protection — The XR13 compressor has an internal overload protector. A hard start kit reduces start current and can extend compressor life when supply voltage is marginal.
- 5 flashes — Control board — Usually traced to power surge damage. Check the 5A fuse on the board and the 24V transformer secondary voltage (should be 24–28VAC at full load).
- 8 flashes — Anti-short cycle — Normal behavior after a compressor shutdown; the board delays restart for 5 minutes to protect the compressor from liquid slugging. Not a fault — just wait.
Step-by-Step Fix
- Locate the LED — Open the service access panel on the XR13 outdoor unit. The control board is mounted near the contactor. The LED flashes the fault code continuously until cleared.
- For 2 flashes (high pressure) — Shut down the unit. Inspect the condenser coil on all four sides — the XR13’s coil can accumulate debris between the fins where visual inspection misses it. Use a fin comb for badly bent fins. Verify the fan is spinning (capacitor test with a capacitor meter is more reliable than a visual check).
- For 3 flashes (low pressure) — Connect manifold gauges. R-410A suction pressure should be 100–115 PSI at 70°F ambient. If pressure is low, locate the leak before recharging — UV dye injection or an electronic leak detector at all joints and the service ports.
- For 4 flashes (compressor protection) — Allow 30 minutes for thermal overload reset. Measure supply voltage at both legs of the disconnect — should be within ±10% of nameplate voltage. Test the dual run capacitor with a capacitor meter.
- Restart and monitor — After any repair, power up the unit and monitor suction and discharge pressures for the first 10 minutes. A properly operating XR13 should have suction around 105–120 PSI and discharge around 280–320 PSI at standard conditions.
Parts Often Needed
| Part | Notes |
|---|---|
| Dual run capacitor | Most common failure on XR13 outdoor units |
| Contactor | Replace if contacts are pitted or discolored |
| Condenser fan motor | Confirm rotation direction (counterclockwise from top) |
| High-pressure switch | Replace if Code 2 persists after coil cleaning |
| Low-pressure switch | Replace if Code 3 persists with correct charge |
| Control board | For Code 5; check fuse before replacing board |
Technician Tips
For Trane heat pump and air-conditioner faults, confirm thermostat demand, outdoor board history, sensor resistance, airflow, coil condition, and refrigerant-pressure conditions before replacing controls or motors.
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
Any investigation of low-pressure or high-pressure faults that goes beyond visual inspection and switch testing requires refrigerant manifold gauges and EPA 608 certification. If the compressor hums but won’t start, test the capacitor first — a failed run capacitor is the most common cause of compressor no-start on XR13 units.