Air Conditioning - minor leak & fluctuating discharge pressure

Ok im a universal certified tech but havent worked in the field since 95.On my home central a/c unit Ruud 3.5 ton i think i have moisture in the system. On a 90 degree day my head pressure goes from 250 to 275 psi constantly rising& falling. I dont have a recovery machine if i take a chance of "pissing" out the refrigerant thru the gauges wont i lose oil? I cant rent a recovery machine so how do i go about doing this? Thanks

You will need to invest in the proper equipment to do this work. If you think there is moisture in the system recover the refrigerant utilizing your shiny new recovery machine into your shiny new recovery tank using a shiny new inline filter drier between the recovery machine and unit. Now replace the units filter drier utilizing your shiny new oxy/acy torch setup. At this point you may take your shiny new vaccum pump and your shiny new micron guage and vaccum down to under 500 microns for several hours to boil out any moisture left in the system, be sure to triple evacuate and utilize your shiny new nitrogen tank/regulator to break the vaccum between pulls. If you cannot pull the vaccum down and it will not hold then you will need to utilize your shiny new heated pentode refrigerant leak detector to find the leak and effect any needed repairs which may include your shiny new oxy/acy brazing outfit. Then simply reverse the process refilling your unit from your recovery tank also again utilizing your shiny new filter drier, any moisture in the old refrigerant will be captured by the filter drier and wallaa mositure free system. Oh yeah and you will need that shiny new electronic scale to be sure that you refill the proper amount back into your unit. Yeah kinda joking around here but I tell you man if you do not have proper equipment you are wasting your time and will probably damage the unit plus the fact that releasing refrigerant is AGAINST THE LAW.