rev up your engines, today I'm gonna talk about why it isn't such a good idea
for people who aren't mechanics to try to use one of these AC recharge kits on
their car, because if not done correctly you try one of these kits you can
actually cause a lot more damage to the system then you will helping it try to
make it blow cold again, now in the old days when cars had what was named freon
but it's actually on just a trade name, technically it's called
r12 refrigerant, it was perfectly fine using a can to refill them then, they were
a different type of system, as an example
when they were low, the receiver drier had a little window on the top of it
clear glass, and when the system that had freon r12 in it, if it was low
you would see a bunch of foam like waves on the beach inside, and all you had to
do was hook up one of these cans and add it in until the foam went away, so then
you knew it was filled correctly to the right amount and you could turn the
valve off and have cold air, but even my 94 Celica, it doesn't have that
system, it uses the newer 134a refrigerant, where you can't look at any
sight glass, you have to use gauges and a scale to do it correctly to have the
right amount of refrigerant, and back in the day r12 refrigerant, some systems
hey they had over three pounds of refrigerant so they had a lot of leeway
if you had not enough or a little bit too much in it, but modern systems use the
134a and they use a lot less refrigerant in
them, everything is metric these days and a lot of them, they only use like four
hundred and fifty grams that's it, so if your off, not only won't it work right
but it can actually do damage to your system, using one of these cans you have
no idea how much you're putting into the system if you're just adding it, you just
know that in this case it says it's got 16 ounces, so you're putting in 16 ounces
but hey how do you know how much it's low, well you don't your just guessing, and
yeah this has a gauge on it, but it's only the low side gauge, and the
important gauge is the high side gauge if the high side of the system gets too
high, boom things can blow up yeah you can read the low-side on these I
mean they're really cheap ones don't have any gauge at all you have no idea,
here at least you get an idea what the low-side pressure is, but still you don't
know what the high side is and that's the important one, that's the high
pressure you get to high pressure things can blow up, and then there's the problem
of getting moisture in the system, they can't handle much moisture our airs
atmosphere is full of water vapor, so even this little hose here when you snap
this on it just snaps on it's easy to put on, you got this much air in the
system, you're actually adding some moisture into the system you don't want
to do that, plus if your system is completely empty,
that means it's open to the atmosphere somewhere where there's a leak, and this
system could be already full of water vapor from air getting inside there,
especially in a human place like Houston so if you just put refrigerant on top of
all that moist air that's in there that's a recipe for disaster where down
the line I've seen people do it corrosion occurs, the compressor locks up,
you can create a lot of problems just adding stuff in willy-nilly with
guesswork, now yeah these things are easy to keep up, you just take off the low
side this snaps right on, then you turn the gauge on to open it up, but as I said
it's so important in a modern car to have the right amount of refrigerant, one
even if you put all this in, this is 16 ounces, let's say it was totally empty
you put in 16 ounces very few system take exactly 16 ounces,
how you gonna measure the rest and the case of the Subaru,
it says attached between 20 and 23 ounces, so even with two of these cans
you'd never be able to guess it correctly, and yes if you're off even an
ounce in a modern car it might not work right, plus like I said you're gonna
inject some humid air with this hose here, it's something that I don't advise
people to do, now this particular Subaru just came over here the system's been
completely empty for months, here's how you have to do it correctly if you want
to make sure it doesn't have a problem you'll hook up a set of AC gauges, one to
the low side and one to the high side, you put the low side blue on the low side
open it up, now you can see here it's got zero pressure so we know the system is
empty, now by law in the United States if you have refrigerant in it,
you're not allowed to vent it to the atmosphere, you have to have a recycling
machine to recycle the stuff, I have one but I don't need to hook it up now
because this doesn't have anything in it then you go to the high side port and put
the gauge on there, that way you'll know if there's a serious problem in a system,
and you see the high price you starting to go way up 300 something psi, you
stop the process of adding refrigerant then try to figure out why the pressures
building up, you just don't start adding and hope, you want to be logical about
this and do it scientifically, now as I said there might be air in the system, so
you take the yellow line it's the feed line and you stick it on a vacuum pump
then turn it on, as it goes into a vacuum and it's near minus 30 pounds, that will
create a vacuum in the system, and once the vacuum is created it sucks
everything out including water vapor when under high vacuum pressure, water
will actually start to boil turn it into a vapor and the pump sucks it out, so you
want to leave this pump on for say 45 minutes or so to take everything out,
now the only way to fill it correctly is to get a reverse scale, this measures how
much refrigerant is in, as it goes in the scale shows how much weight is taken out,
0.55 -0.65 kilogram, I always put the maximum point six five kilogram in, and I
do use kilograms, you're really going to get an accurate reading and it'll be
filled right, open it up and it's starting to fill the system, as you can
see down here it's filling up and we want .65 kilograms, because
that's what it says right here is the max, then we start up the car turn the
a/c on full blast, and then one this says .65 we're done, do it with the
tank pointed up, you want to do with vapor, if you turn it upside down you get
liquid, it charges faster but that liquid can destroy stuff, always use the gas
it's a safer way to fill it up, yeah it's gonna take more time, but really it
doesn't take all that much more time then when it gets to .65 we
shut the valve off, and there it goes here we go
nice cold air, now how long will it last well who knows, this Subaru is 16 years
old, the original owner she's never added refrigerant, so if
you gotta add it once every 16 years that's not too bad, only time will tell
like that, but at least we know now it was done right, so now you know I don't
advise people to use those self refill ac kits, but this is mechanics
Monday and I got to give something away but I'm not gonna give those away,
instead I'm gonna give away an a/c vacuum pump, to have a chance to win
place a clean non offensive comment on the YouTube comments below, and a winner will
be chosen randomly by computer, to get a nice vacuum pump so they can fix their
AC the right way, so if you never want to miss another one of my new car repair
videos, remember to ring that Bell