What It Means
Circuit B condensing temperature sensor out of range.
Carrier Packaged Unit
Carrier Packaged Unit Error Code 65
Troubleshooting guide for the Carrier Packaged Unit system fault 65.
Possible Causes
- Damaged circuit B condensing sensor wiring or connector.
- Failed or out-of-calibration thermistor.
- High condensing temperature from refrigerant overcharge.
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
Condensing Temperature Failure - Circuit B. Condensing temperature is outside the valid range and fans are controlled from outdoor temperature.
All Recorded Causes
Check circuit B condensing temperature sensor wiring and connector. Measure sensor resistance against temperature/resistance chart. Inspect for refrigerant overcharge causing high condensing temperature. Replace sensor if out of spec.
Verify Before Replacing Parts
- Confirm the exact Carrier model family and outdoor packaged units context before acting on a generic code description.
- Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since check circuit B condensing temperature sensor wiring and connector.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm measure sensor resistance against temperature/resistance chart.
- After the correction, run the system long enough to confirm the outdoor packaged units fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Carrier Packaged Unit diagnostics step-by-step — so you confirm the cause before swapping parts.
