What It Means
Hard lockout — unit shut itself down on a serious fault and won't restart on its own.
American Standard AC & Heat Pump
American Standard AC & Heat Pump Error Code Green LED
(Intermittent Flash – 1 flash every 4 sec)
Troubleshooting guide for the American Standard AC & Heat Pump system fault Green LED (Intermittent Flash – 1 flash every 4 sec).
ACLogics Fix American Standard code Green LED (Intermittent Flash – 1 flash every 4 sec) See how ACLogics handles it → Fix Green LED (Intermittent Flash – 1 flash every 4 sec) step-by-step
Possible Causes
- High- or low-pressure cutout on the outdoor unit.
- A sensor fault reported by the outdoor control board.
- A communication fault between indoor and outdoor boards.
- Some other fault serious enough to trip a hard lockout.
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
Hard lockout active — the outdoor unit has shut itself down after detecting a serious fault (such as a high- or low-pressure cut-out, or a sensor fault) and will not restart on its own. Unlike the Green fast-flash power-up delay, which clears automatically within seconds, this lockout holds until the underlying fault is resolved and power is manually cycled at the disconnect or breaker. While in lockout, the red LED simultaneously flashes the specific numbered fault code (e.g. Red 7, Red 17) identifying the cause, so both LEDs must be read together to diagnose the issue.
All Recorded Causes
The system is locked out due to a serious fault (e.g. high/low pressure). Count and record the accompanying red LED flash pattern before doing anything else — that number identifies the actual fault driving the lockout (pressure, sensor, communication, etc.) and should be looked up and addressed on its own terms. Once the underlying issue is corrected, clear the lockout by cycling power to the outdoor unit at the disconnect switch or breaker for a moment; power cycling is usually required to reset after resolving the issue. If the unit immediately re-locks with the same red code after a reset, the root cause hasn't actually been resolved and a qualified technician should diagnose it further rather than repeatedly power-cycling the system.
Verify Before Replacing Parts
- Confirm the exact American Standard model family and ac and heat pump context before acting on a generic code description.
- Confirm board LEDs, wiring polarity, and model compatibility before replacing control boards — this American Standard fault points at the system is locked out due to a serious fault (e.g.
- Check for intermittent communication faults caused by connectors, moisture, or damaged harnesses, and rule out high/low pressure).
- 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 American Standard code is on?
ACLogics has guided diagnostics for 36 American Standard fault codes and asks the right questions to narrow it down.
