Error F4 in Air Conditioners: Causes and Solutions

The F4 error code in air conditioners is commonly associated with issues in the EPROM memory of the electronic control board. This memory plays a crucial role in the system’s operation, storing essential data such as factory settings and configurations.

Below, we explain the steps to diagnose and resolve this issue effectively.

Steps to Resolve the F4 Error

1. Turn off the unit
   • Turn off the air conditioner and disconnect it from the power supply.
   • Wait a few minutes before reconnecting it.
2. Check the error behavior
   • Power on the unit and observe if the F4 error code appears immediately.
   • In some cases, if the problem lies specifically in the EPROM memory, the system may display various error codes before stabilizing on F4.
3. Visual inspection of the external electronic module
   • Locate the unit’s external control board.
   • Perform a visual inspection of the controller and identify the integrated circuit near the EPROM memory, typically with eight terminals (four on each side).
4. Check resistors near the EPROM
   • Conduct a detailed measurement of the resistors located near the EPROM memory.
   • If any resistor shows a value outside its expected range, replace it carefully.
   • After replacing the resistor, restart the unit to check if the F4 error has been resolved.
5. Replace the EPROM memory
   • If the F4 error persists after replacing the resistors, the issue is likely with the EPROM memory itself.
   • In this case, replace the defective memory with a new one programmed with the appropriate data or use an EPROM taken from another control board of the same model.

What Is EPROM Memory and Why Is It Important?

EPROM (Erasable Programmable Read-Only Memory) is a type of memory that allows data to be written, erased, and rewritten electronically. Its key feature is that it is non-volatile, meaning it retains stored information even when the power is off.

In air conditioners, EPROM memory stores factory settings, unique device data, and, in some cases, firmware containing the instructions required for the system’s operation.

Programming the New EPROM

To ensure the air conditioner operates according to the manufacturer’s specifications, the new EPROM must be programmed with the original data. This ensures the device maintains its original characteristics and performance.