The error code U4 on a Daikin air conditioner means that there is a communication error between the indoor and outdoor units. This could be caused by a number of things, including:
- A loose or damaged connection in the wiring between the indoor and outdoor units.
- A fault with the indoor or outdoor control board.
- A power surge or power outage.
To fix the U4 error code, you can try the following steps:
- Check the wiring between the indoor and outdoor units. Make sure that all of the connections are tight and secure.
- If the wiring is okay, then you can try resetting the indoor and outdoor units. To do this, turn off the power to the air conditioner and then unplug it. Wait for a few minutes, and then plug the air conditioner back in and turn the power back on.
- If the air conditioner still displays the U4 error code, then you may need to call a qualified technician to diagnose and repair the problem.
Here are some additional tips for fixing the U4 error code:
- Make sure that the indoor and outdoor units are properly aligned. If they are not, then this can cause interference with the communication signal.
- Keep the air conditioner's vents and filters clean. A dirty air conditioner can restrict airflow and cause the control board to overheat, which can lead to communication errors.
- If you have recently had a power outage, then the air conditioner's control board may have been reset. In this case, you will need to reset the air conditioner as described in step 2 above.
If you have tried all of the above and you are still getting the U4 error code, then you may need to replace the indoor or outdoor control board. These components are relatively expensive, so it is important to make sure that you have exhausted all other troubleshooting options before replacing them.