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 amazon.com If you want to help support
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