L1
Armstrong Air
Line Voltage Loss or Phase Fault (for 3‑phase commercial Armstrong Air units)
Outdoor unit completely dead, L1 or line-voltage fault indicated on control board, no LED activity
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Tripped breaker or blown fuse feeding condenser, Open disconnect, Loose line-voltage connections, Phase loss on 3‑phase supply
How to Fix / Troubleshooting
Safety first: This involves high voltage. If you are not trained, do not remove live covers. Always turn off the breaker before opening panels.
Steps:
- 1. Check breaker: Locate the AC condenser breaker in the electrical panel. If tripped, reset once. If it trips again, do not continue resetting—there is a fault.
- 2. Inspect outdoor disconnect: Ensure the pull-out or breaker at the outdoor disconnect is fully inserted and ON.
- 3. Verify power at unit: With a multimeter and proper PPE, a qualified person can check for correct voltage at the line side of the contactor.
- 4. Tighten connections: With power off, inspect and tighten all lugs at the disconnect and contactor. Look for burned or discolored wires.
- 5. For 3‑phase units: Confirm all three phases are present and balanced. Phase loss requires an electrician or utility intervention.
- 6. If L1 persists with correct power present: The control board’s line-sensing circuit may be damaged and require replacement.
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Repair Difficulty
Professional Required
5/5
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