What It Means
Liquid line pressure sensor open or shorted circuit fault.
Trane AC & Heat Pump
Trane AC & Heat Pump Error Code Red 12 Flashes
Troubleshooting guide for the Trane AC & Heat Pump system fault Red 12 Flashes.
ACLogics Fix Trane code Red 12 Flashes See how ACLogics handles it → Fix Red 12 Flashes step-by-step
Possible Causes
- Damaged or loose pressure transducer wiring.
- Defective liquid line pressure sensor.
- Abnormal system operating pressures.
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
Liquid line pressure sensor fault (open or shorted).
All Recorded Causes
Check the wiring to the pressure transducer. Replace the sensor if confirmed bad; a technician should verify system pressures and operation.
Verify Before Replacing Parts
- Confirm the exact Trane model family and ac and heat pump context before acting on a generic code description.
- Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since check the wiring to the pressure transducer.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm replace the sensor if confirmed bad; a technician should verify system pressures and opera….
- After the correction, run the system long enough to confirm the ac and heat pump fault does not return under normal load.
Not sure which system this Trane code is on?
ACLogics has guided diagnostics for 36 Trane fault codes and asks the right questions to narrow it down.
