I am new to air conditioning and this forum,

been a plumber and electrician for a long time now, moved over to Spain (from UK) 3 years ago, my only AC experience is fitting about a dozen split units, dakin, hitachi, verhal, nothing complicated.


so to my beginners questions

1st brazing
this is embarrassing as a plumber, but i have never braised, though with over 25 years in the trade i have seen my share, I will only be working on domestic units with a max 5/8" pipe
Do you use flux?
I assume you clean the joint prior to brazing?
I have only seen you use ex panders to make the joints, I cant find ex panders for 1/4" pipe?
can you use pre made joints?
I have seen locally (only on 1/4")just map gas being used, I had always assumed you needed a small oxy kit to braise?


How do i determine if there is enough gas in the unit?
not new units, pre installed units, I had a leak on a unit, not a joint but a duff o'ring on a gauge hose, I had no idea how much gas had been lost so i just added more gas until it started working properly (here's you all cringe)
I have bought 3 books on AC/Refrigeration but none give any real info on this (for a modern split unit)

any info on this would be appreciated, maybe a good book recommendation

thx
Steve