I have 2 Hampton Bay ceiling fans on my outdoor patio. They were installed by a licensed electrician. The box on the side of the house when opened shows them labeled A & B also the remotes are labeled A & B

B is working just fine. I changed the batters in the A remote due to fact the light and fan were not turning on. It is still not turning on by remote. The LED on the remote is lighting and registering what I am asking it to do. On fan A I have a pull cord also. When pulled it does turn on and off. There is not pull cord on the light fixture to test.

How do I test the sensor on the wall unit to see if it is bad?

Could it be another problem? Suggestions please

Does the remote have a series of switches on it? These are called "Dip Switches". If even one of those switches has been changed, the remote will transmit of a different freq. than the receiver inside the fan and the transmission will be ignored.

If something is not working you should call the installer...it is his responsibility to make
his installation work properly. There should also be a 1 year warranty on parts and labor.