Miswiring or serial signal: the outdoor unit's serial signal was missing for 6 minutes. The left lamp blinks 0.5 second on and 0.5 second off, with no counted pause.
A steady 0.5-second blink of the left lamp, with no 2.5-second pause, is table 9-4 row 1: miswiring or a missing serial signal for 6 minutes. It is not a counted blink. The manual warns that miswiring can damage the indoor control board.
Likely causes
- Miswiring between the indoor and outdoor units
- Serial signal from the outdoor unit missing for 6 minutes
Safe checks for Continuous blink
- Confirm you are seeing a steady half-second blink, not a counted pattern with a 2.5-second pause. Write it down
- Switch off the breaker and the outdoor disconnect. Do not move wires on the terminal block
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
The manual sends this pattern to the miswiring and serial-signal check, and it warns that miswiring can damage the indoor control board. Call a licensed HVAC technician.
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