Steps to Vacuum and Charge Refrigerant on a Mini Split Unit!

Hey guys this is Craig Migliaccio with AC 
Service Tech and today what we're going over is   how to vacuum a mini split unit down below 500 
microns in preparation for adding refrigerant   from the bottle or from the service valves I'm 
going to show you how we got to this vacuum   level during the standing vacuum test because 
this proves that there is no leaks there's no   water there's no air and there's no nitrogen 
in this system so this system will be ready for   refrigerant so I'm going to show you all the 
connection points and preparation and running the vacuum pump This video is sponsored by our 
friends at superior AccuTrack and I have a   link to the videos I made using their ultrasonic 
leak detector down in the description section below After connecting your refrigerant tubing 
from this outdoor unit to the indoor head unit   that's when you pressure test this tubing so you 
need to pressure test before you vacuum and then   you vacuum before you add refrigerant into the 
system so pressure testing what you're doing is   you're searching for leaks may be at the flare 
joints and you want to find those leaks before   you vacuum because you don't want to vacuum 
the system the whole point is that when you're   vacuuming you're trying to remove the moisture 
remove the air from the system so if you have a   leak and you connect your vacuum to this port 
right here and you're you're pulling a vacuum   it's going to lower in pressure it's going to turn 
into a vacuum is going to pull all the humidity   that's in the air out here it's gonna pull it 
in through the leak so you don't want to just   vacuum pump without pressure testing now I usually 
pressure test by connecting a valve core removal   tool over here and I like to remove the valve core 
at this port first before I even pressure test so first things first this is a 5/16 port right 
here and so this valve core removal tool will fit  This is a quarter-inch valve core removal 
tool so this will not work in this situation right here   Now remember that we don't actually 
have to connect this right now because this is   empty tubing if if this did have refrigerant in 
it and we wanted to replace the valve cord then   we would need the entire component right here 
but all we need right now is just the back so   we're gonna take the back and we're going to 
pull the valve core out since this is empty So there's the valve core what we're going to do is 
we're going to connect this valve core removal tool  and what I like to do when I'm pressure 
testing is I would just put this valve core   removal tool in place and I connect to a quick 
connect test gauge right on to this port So then I'll connect my refrigerant hoses right to here 
and so I add the nitrogen in then I can shut it off  then I can read my pressure over say a 10-20 minute period to see if it's going to fall or not so after that's done that's when I'm hooking 
the the vacuum set up so to hook the vacuum setup up  I'd like to use a second valve core removal 
tool and the reason for that is is so that I can   isolate my vacuum gauge so I hook this other 
valve core removal tool right up to this port and I make sure that there is no Schrader valve 
in the port of my valve core removal tool Then I connect my vacuum gauge right on to this second 
valve core removal tool and the reason for that   is is just so I can shut it off as I break the 
vacuum with refrigerant from the bottle or from   the system and that refrigerant and oil will not 
contaminate the vacuum sensor in here So I can read a vacuum by having this open and while
the vacuum pump's running I'll be able to read   the vacuum and then I can shut this valve off 
and I'll read the vacuum that's actually in the   system with the vacuum pump off so that's why I 
like to use this setup Make sure that you don't  put the valve core back into the port again until 
after you have positive pressure in this system   from the refrigerant so you're not putting this 
in until you're just about all done so if you've   tried to put this back in before you have positive 
pressure in here from the refrigerant you're going   to accidentally lose part of your vacuum Now the reason that we're removing this valve core in the first place   is to make sure that we're removing 
the restriction so that we can have a deeper and faster vacuum  this is a 4 CFM vacuum pump and just 
so you know all the tools using this video are linked   down in description section below.

So we're going to 
leave these two caps on and we're going to just   remove this top cap we're going to install a 3/8 
so this is a 3/8 vacuum hose with a 3/8 end and   this side has 3/8 to 1/4 inch now you could 
use a standard quarter inch hose you could use   a 3/8 hose that has two 1/4 inch connections 
and we can connect here and right over to here but   this is what we're using today so we're gonna 
go ahead and connect right on to this end of   the valve core removal tool and we want to make 
sure that all of our other connections are snug   before we start our vacuum pump so that's snug 
this is snug so everything should be ready and   then we can go ahead and turn our vacuum pump on 
as soon as we turn our vacuum gauge on So I'm just waiting for this to start up and what it'll do is 
it'll end up reading the micron level and you can   change it just by pressing the unit's value right 
here so we're gonna turn our vacuum pump on now Very soon you're gonna see 
it reading the micron level Now as this is pulling down what I'm gonna 
do is I'm gonna turn these valves off and   then on again once we get down to maybe 700 
or 500 microns and the reason for that is is   there's a little bit of air trapped on the ball 
valve on the inside of these pools So I'll just go ahead and I just close them just once and 
reopen them right away so we're pulling down   below 500 microns I like to target around 200 
microns or maybe 150 microns and you could do   a triple evacuation if you if you needed to 
but we're going to prove that we are able to   hold the correct vacuum level with just a single 
evacuation so I'm just going to close this again So now I've turned a vacuum pump off and we're 
reading the true vacuum level inside the tubing here  now the reason that the micron level is 
going up is because we have coming from here   is where we're pulling the vacuum but we're 
pulling the vacuum through the indoor head   unit and all the way over to here so right now 
our vacuum is equalizing between this side and this side  So I just want to time this and 
so you know during the standing vacuum test   this vacuum gauge could go off because if the 
vacuum gauge is only going to stay on for say   10-15 minutes and then it's going to shut off 
just to save battery life so I'm just gonna   let this timer run and we'll see how much 
this vacuum this true vacuum level rises So you see that we're at ten minutes so I'm just 
going to go ahead and stop this and you see that   our vacuum had to equalize first and then once 
the vacuum was the same on both sides the vacuum   level hasn't risen so that means that we are 
good and we're ready for a refrigerant so what   I'm gonna do next is get our refrigerant bottle 
and hose ready so that we can add refrigerant   into this port right here now normally all we 
would need to do is just go ahead and get ready to   open these valves right here so what I typically 
do is I valve off my vacuum gauge so I don't get   refrigerant oil into the sensor in there but 
basically you could just take your your allen wrench   and then open this up counterclockwise 
in order to allow the refrigerant from this   outdoor unit into here but in the case where 
you have extra line set added past the maximum   amount that the unit has refrigerant for so for 
instance it'll say the minimum and maximum line   set lengths and so if you're above the maximum line 
set length what they say to do you're gonna have   to add refrigerant into the system so say we had 
to add 10 foot of refrigerant so that's a 10 foot   for the liquid line and 10 foot for the vapor 
line so right here you see that we have R410a and 1/4 inch what we have is 0.2 so 
0.2 times an extra 10 foot that would be two   ounces of r410a refrigerant and down here you see 
the vapor line size of 3/8 and that is 0.24 so this right here is 0.24 ounces so 2.24 ounces is how much we have to add   to this system so this chart is actually found in 
our refrigerant charging and service procedures   for air conditioning book so that's our book right 
there you can check that out over at our website   So first thing here we're going to end up taking 
this refrigerant bottle and you want to make sure that you have a valve on the end and I don't have 
a valve core depressor in the end of this hose so   our valve is off, our bottles in the upside down 
position because we want to make sure that only   liquid comes out of this tank because it's a 50-50 
mix of two different refrigerants so it will come   out of the bottle as a correct mix if it comes 
out as a liquid so now that we have that we're   ready with that we can go ahead and get ready 
to zero a scale but now we're going to get the   air out of this hose right here so we're just 
gonna open this up slightly to get the air out we don't want to put air in our system   Okay so 
now we have just our liquid refrigerant coming   through here and what we're gonna do is we're 
going to attach right here onto the end of this valve core removal tool  now while this valve is 
in the off position we're going to go ahead and   disconnect our vacuum hose and we're gonna take 
our hose here we're going to connect it in   Now we want to purge the air out right here so we'll go 
ahead and open this up Now we have refrigerant all the way over to this hose you want to go ahead 
and turn the scale on So you see the scale is   zeroed out and now we're going to go ahead and 
turn this off and we're going to open this up So there we have our two point three ounces 
of refrigerant and so now we're good at this point we can go ahead and disconnect right 
here so we will turn our valve to the off   position and then we're going to take our hose 
off and and then after that we can go ahead and   open these valves up counterclockwise at that 
point we would just go ahead and put our valve   core back in and then we're going to leak 
check our valve core and then we are we're   good to go and we can go ahead and start 
the unit up so I'm just going to shut this off  take our valve core we're going to put 
that back in and we're going to open this up   and we're going to purge a small amount of 
air right here we're going to screw back in so now that there's pressure in there 
you need to push forward as you screw this in Now we want to go ahead and just leak check this 
before we just take this off over here so we turn   this valve to the off position and then we want to 
see to make sure that this valve core is resealed back in here and it's holding the pressure back 
now we can test it with bubble leak detector so   you can either apply bubble leak detector right 
in the end and sometimes you'll have a large glob   and it'll fall out or you could take a cap and 
drill a little hole in the end so this is like   a little tester that I use and then you want 
to see if it's gonna blow any bubbles out if it doesn't blow any bubbles out then we're good 
and we can go ahead and just disconnect right here  So you want to wait for maybe 1 to 2 minutes 
just to make sure that you don't have any bubbles being blown   and there is no bubbles so now we're 
gonna go ahead and just disconnect this So then you're gonna put your allen key in and you're 
gonna turn that counterclockwise almost all the   way back and this one too you're gonna turn it 
so once it starts getting snug you're going to   stop on both of these and then you can go ahead 
and put the caps back on here here and then also   one on your valve core and then you can go ahead 
and turn the system on And make sure to check out a refrigerant charging and service procedures 
for air conditioning paperback and ebook both   available at our website at ACSERVICETECH.COM.


We also have the paperback available over at  If you want to help support 
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see you next time at AC Service Tech channel.

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