Hello fellow engineers!

I am working on a split AC from Daikin model R125FJ7W1 right now. It is about twenty years old.

This year, after a little service, it was running only for 5 minutes every 5 minutes, so I started to look into the matter.
Recently, when turning the electricity on, it didn't start normally but the display showed "88". (The fans won't activate ever since that error.) From what I know that is not a normal start. The indoor units started as normal, though. Now when I changed a special switch in the connected indoor unit and changed it back after a minute (see pictures), the display would normalize and show an E0 error right after that, which would lead to the safety devices. I would like to know from you how I might be able to specify the error. Shortly pressing the pump down-button (yes I know, sorry, shouldn't have done that) activated the compressor. Can i exclude it from my search?

Pictures:
http://imageshack.com/a/img924/2606/kWgqsg.jpg
http://imageshack.com/a/img924/1046/Ut0kyE.jpg
http://imageshack.com/a/img923/4915/ZDpx8x.jpg
http://imageshack.com/a/img922/5597/xY24OW.jpg
http://imageshack.com/a/img922/1662/jn3nSb.jpg
http://imageshack.com/a/img922/7584/93Ilc7.jpg
http://imageshack.com/a/img924/4488/95cn9b.jpg

Thank you a lot for your time!