The error code 'F4' means that the memory chip on the outside PCB has failed.
To fix the problem you'll need to isolate the power from the mains for 2 minutes, then restart.
If the problem still exists then the outdoor main PCB needs to be replaced. To get a new outdoor main PCB you'll need to contact us via email at info@airconditioningcentre.com or call us at 0370 3344 556.
ANY WIRING OR CLEANING OF CONNECTIONS REQUIRE THE POWER TO BE ISOLATED BEFORE WORKS COMMENCE.