For solder style a/c condensers is it mandatory to use heat absorbing paste? the reason i ask is that i have always used it without question.Of course today being saturday the wholesalers are closed and i find myself with a two year old half used tube that looks good but I'm not sure.Anyhow i once had the pleasure(not really) of having to replace the valves on a condenser that had been overheated by someone elses crappy solder job.He didn't use paste and while i will use it i don't know if it's still good.Getting back to the crappy solder job this guy did't belive in evacuating the system either just filling it with nitrogen and opening high side condenser valve and pushing it out.He honestly looked at me like i was from another planet for using a vac pump.Guess i'm old school but ive never and i mean never had a joint leak.Im using a tubo torch not oxy/acet.Need this info quick please.