What It Means
Low-pressure switch opened, cutting out system operation.
Trane AC & Heat Pump
Trane AC & Heat Pump Error Code Red 7 Flashes
Troubleshooting guide for the Trane AC & Heat Pump system fault Red 7 Flashes.
Possible Causes
- Dirty air filter or obstructed indoor airflow.
- Iced-over indoor or outdoor coils.
- Refrigerant leak.
- Defective low-pressure switch.
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
Low-pressure cut-out fault. (Code 79 on some controls.) The system’s low-pressure switch opened.
All Recorded Causes
Check that the air filter is clean and indoor airflow is not obstructed. If coils are iced, allow them to thaw. If the error continues after reset, there may be a refrigerant leak or bad pressure switch; contact a qualified technician.
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 that the air filter is clean and indoor airflow is not obstructed.
- Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm if coils are iced, allow them to thaw.
- 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.
