What It Means
Outdoor coil temperature sensor reading is out of valid resistance range.
Bryant Heat Pump
Bryant Heat Pump Error Code 55
Troubleshooting guide for the Bryant Heat Pump system fault 55.
Possible Causes
- Faulty outdoor coil thermistor.
- Corroded, pinched, or loose sensor wiring harness.
- Sensor unseated from coil clip.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
Coil Temp Sensor Fault. The control detects the outdoor coil temperature sensor reading outside its valid resistance range, disabling coil-temperature-dependent functions such as defrost initiation/termination and low-ambient compressor protection until the sensor is repaired. The outdoor unit can continue to run but loses the coil-based logic that would normally protect it during cold-weather heating operation. This is a single-sensor fault, which distinguishes it from code 56 (OAT-OCT thermistor out of range) — 56 fires when the board compares the coil sensor and outdoor air temperature sensor against each other and finds their relationship implausible without being able to isolate which one is bad, whereas 55 points specifically at the coil sensor itself. If both 55 and 56 appear together, start with the coil sensor.
All Recorded Causes
Ohm out the outdoor coil temperature sensor and compare the reading to the manufacturer's temperature/resistance chart at the coil's current temperature. Check sensor wiring and connector for corrosion, pinched insulation, or loose pins. Verify the sensor is properly seated in its coil clip with good thermal contact — a sensor that has slipped out of contact with the coil will read ambient temperature instead of coil temperature and can trigger this fault even though the sensor itself is fine. Replace the sensor if resistance is out of specification after ruling out a seating or wiring problem.
Verify Before Replacing Parts
- Confirm the exact Bryant model family and heat pumps context before acting on a generic code description.
- Confirm filter condition, blower operation, and coil cleanliness before replacing any controls — start by ruling out whether ohm out the outdoor coil temperature sensor and compare the reading to the manufacturer's….
- Measure airflow-related readings that match the symptom, such as temperature split or static pressure, and check whether check sensor wiring and connector for corrosion, pinched insulation, or loose pins.
- After the correction, run the system long enough to confirm the heat pumps fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Bryant Heat Pump diagnostics step-by-step — so you confirm the cause before swapping parts.
