Operation LED blinks 2 times (Off) and Timer LED shows 01 — Serial reverse transfer error at startup.

What does Operation Off 2 Times / Timer 01 mean?

When the system starts, the indoor unit (evaporator) and outdoor unit (condenser) are not communicating. This indicates a problem with the serial communication wiring.

• 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

   Power off the system at the circuit breaker and check all wiring connections between the control panel, condenser, and evaporator.

2. 2

   Ensure all wire connections are secure; avoid using simple wire nuts and splices.

3. 3

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

4. 4

   If the error persists after checking connections and voltage, professional service may be needed.