/diy/ - Do It Yourself

Does anyone know why generic aircon remotes sometimes forget which code works for my aircon? I've got a Panasonic R410A and I've had to buy a few different aircon remotes, I bought this black one that only worked for a few weeks then would forget the code so I had to look it up and put in a new code which was a hassle, I bought this grey one that only works for a few months then the same thing happens, I have to search for a new code that'll work, the list is 2000 and it can take ages at times. I'm sick of it.