Operation LED blinks 4 times (Off) and Timer LED shows 13 — Serial forward transfer error at startup.

What does Operation Off 4 Times / Timer 13 mean?

At system startup, the indoor unit (evaporator) and outdoor unit (condenser) are not communicating.

• Wiring between the control panel, condenser, and evaporator is incorrect or loose.
• Incorrect voltage supplied at the panel, condenser, or evaporator unit.

Click steps to track your progress.

1. 1

   Reset the power to the unit by turning it off at the circuit breaker, waiting 30 seconds, then turning it back on.

2. 2

   If the error reappears, check all wiring connections from the control panel to the condenser, and from the condenser to the evaporator.

3. 3

   Verify that the correct voltage is supplied to the electrical panel, condenser, and evaporator units.