Trane AC & Heat Pump Error Code Red 17 Flashes

Full Diagnosis

High-pressure cut-out fault (Error 80 on some communicating control displays) — the discharge-side high-pressure switch tripped and opened, shutting the compressor down to prevent damage from excessive head pressure. This is the mirror-image fault to Red 7 Flashes (low-pressure cut-out), and the two point to opposite root causes: Red 17 almost always traces back to restricted heat rejection (dirty coil, blocked airflow, failed condenser fan) rather than the refrigerant-charge or metering issues behind a low-pressure trip. The compressor won't restart until pressure drops and the switch resets, and the unit can go into hard lockout if it trips repeatedly.

All Recorded Causes

Shut the system down, then inspect and clean the outdoor condenser coil of dirt, leaves, and debris, and confirm the condenser fan motor spins freely and reaches full speed. Check for anything blocking airflow around the outdoor unit, such as shrubs, fencing, or snow. Let the unit sit until pressures normalize, then restore power and reset. If the code returns on the next cycle, don't keep resetting it — have a technician verify refrigerant charge, check for an overcharge or non-condensable condition, and test the high-pressure switch itself for a false trip.

Verify Before Replacing Parts

1. Confirm the exact Trane model family and ac and heat pump context before acting on a generic code description.
2. Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since shut the system down, then inspect and clean the outdoor condenser coil of dirt, leaves, a….
3. Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm check for anything blocking airflow around the outdoor unit, such as shrubs, fencing, or s….
4. After the correction, run the system long enough to confirm the ac and heat pump fault does not return under normal load.