Well You Did It Quiet Good....! Yes This Vacuum Pump COmes Quiet Handy And Is Effective.....Right Investment...I Am Also Looking For One
ANyways......For Vacuum.....Mostly Pull Vacuum On Both Low Pressure And high Pressure Line....Timing Is All Good...Do It For 1 Hour...!
Then Close Vacuum Pump So As Your Valves On Gauge Set And Look For Vacuum Drop On Low Pressure Side.....Leave It For 15-20min...The Pullled Vacuum Which Will Be Like Almost 29-30 HG..SHould Not Drop......If It Does.....There's A Leak
( Vacuum Reading Only Shows On Low Side Gauge...High Side Gauge Don't Have Vacuum Readings...) If It Goes All Good....
If You Want To Change Dryer.....1st Pull Vacuum For 15min On System And Close Gauge And Check For Leaks....If No Leaks Found....Then Open The Old Dryer And Install The New Dryer fast As Good As Within 2-3min.......(Don't Open new Dryer 1st ..Open It When U Just Need to Install) After Installation...Pull Vacuum For Good 1 Hour On Both Suction And Pressure Line.......! After Vacuum...Just Close The Valves And Pump.....Disconnect The Valve And Install It Fast In Your Charging Cylinder........And STart You Car And A/C....
Need To Add Compressor Oil In Small Amount If You Evacuate The Whole System(With Refrigerent ...Oil Is Also Lost )
From Here...Note That There's 3 Method You Can Do
No 1:: Weight Method.....If You Car Is All ON OEM Factory Fitting Pipes And System.....There's Should Be Refrigerent Type And Its Quanity Mentioned On The Car (Sticker Somewhere Or Inside Manual Or Ask HONDA 3s).......! Simply Charge That Weight Of Gas.....(+/-3-5%)....Easy Way Out
No 2:: Pressure Check :: Like Mostly A/C Technicians Do......Just Have A Good Guess And Charge The Gas....Note Pressure Readings And Cooling Inside....Checking Duct Temp And Tweak It.....!
No 3::Sub Cooling Technique:: Used In TXV Type Metering Systems........Ideal To Calculate Effeciency Of System.......Note The High Pressure Line reading And Convert It Into Temp Using P/T Chart......Using Effecient Remote Probe Type Or Clamp Type Thermometer.....For probe..Cover It Nicely After Connecting With Line To Get Effecient Stable reading...
Note The Temp Of Pressure Line....(Closer To Where You Read Pressure From) ....
The Sub-Cooling Should Be Like 9-12 Degrees F....! Adjust Accordingly By Charging Or Releasing Excess Refrigerent....!!
Note:: You need Extremely Effecient Line Temp Reading Else You Will Have Innaccurate Readings Resulting In No Good Calculation..Also The Condensor Effeciency Should Be Kept In Mind And It Depends Also On Your AMBIENT Temp...Yes That Changes During Day Time And Night ..The Difference Can Come As Expected That's Why Its Mostly Used In Home Air Conditioning SUperheat And Sub-cooling Where Everything Is Fixed.(Outlet Temp....Inlet Temp...And So)
The Best Way Is To Add Refrigerent By Weight And Adjust (+/-5) With Pressure And Ambiet Temp ALong With Duct Temp....Rule Of Thumb Say You Will See A Difference Of 25 Degree Celcius B.w Ambiemt And Duct Temp
Hope This Helps