DIY A/C Recharge kit for 2002 Sonata GLS

All,

Have any of you done a recharge on your A/C unit? Mine seem to have
run out and needs to be charged. If you've done it, do you recommend
using one of the kits available at an auto-part store (Murray's,
AutoZone, etc.) or have it done by a pro? I've been told the kits are
pretty easy to use so I would like to learn to do it myself. Thanks
for any help.

- Thee Chicago Wolf

 

To do it right, you need to start from scratch, which means you need a good
set of gauges and know how to use them. You also need a vacuum pump to hook
up to the system, which will cost you about $400 or so. You really do need
to know the procedure so get a shop manual for the car. If you do it wrong,
and open up the high pressure side to the can of freon, you're dead! It's
really not that hard but you just need to know the steps and precautions.

 

Sorry, but you don't need a vacuum pump. If you have good gauges, hooked
up to the right ports, know the ambient air temp., and how much charge the
system is supposed to have, you can fill the system properly without a
problem.

Eric

 

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You need a good sensitive refrigerant scale. Virtually all automotive AC
systems are charged by weight, not pressure/temperature.

gerry

 

From the factory, yes. In the field, it can actually be better to use
pressure/temperature. What do you propose? Evacuate the entire system and
add X ounces of refrigerant?

 

I believe that is the correct way to do it. That obviously isn't what
happens with the DIY kits.

Matt

 

Absolutely, it is the right way to do it. We were talking about DIY from
the start, or so I thought. Although gauges can cost hundreds of dollars,
you can usually find someone that will let you borrow a set, and then you
can just use a can of R-134a from an auto supply.

Eric

 

You might not need a vacuum pump for your AC service, but I sure do.

Of course, I like my AC cold and my pumps happy and long lasting. Iced
up orifice tubes suck.

JS

 

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Weigh in is the ONLY proper way!!! That is also why legal recharging
places have recovery/recycle equipment. In the US, the EPA actually
requires 609 certification to work on MVAC equipment such as an
automobile. "Recharge kits" exist because R-141a does not need a
certification to purchase and the EPA overlooks the private usage.

Weigh-in is the only way to get a full charge without overcharging!

Automotive systems use an accumulator or receiver and TXV metering.
Since this setup keeps a reserve of liquid, the amount of reserve can
not be determined via pressure. Too little and you will get less than
desired capacity. Too much and you get liquid in the compressor and
destroy it. Pressure remains the same without regard to liquid level in
the receiver or accumulator.

gerry

 

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Automotive AC's don't use orifice tubes, they use TXV's for metering.

gerry

 

Aftermarket freon refill kits should BE BANNED. They are dangerous in
the hands of the inexperienced. Further, the average consumer doesnt
have the knowledge on how to properly recharge an auto a/c , doesnt have
the tools/guages nor knows how to read them and understand the
relationship between pressure and temperature of R134 , will most
likely end up putting air as well as freon into the system and
eventually causing problems , etc.... Spend the money and have a
professional do it --- dont go to your local Oil Change place
either...go to a proper Service Station or the Dealership you bought the
car from . If you are constantly adding freon to your system, have it
electronically leak checked during your recharge visit.

 

'Sorry, but you don't need a vacuum pump. If you have good gauges,
hooked up to the right ports, know the ambient air temp., and how much
charge the system is supposed to have, you can fill the system properly
without a problem.
Eric '

REPLY: If the system is totally empty, you WILL need a vaccuum pump to
rid the system of air and moisture and do it correctly. Further, you
dont 'fill' an auto a/c system (to the top) ; it has to be accurately
metered in and depends on a variety of factors . You will NOT know how
much freon to put in unless you weigh in the EXACT amount which requires
a Charging Cylinder that is marked off in lbs and ounce increments ..
which requires you to know how to use it properly ; if y ou just add
freon from a store bought kit , you are only guessing . If youre a
consumer, stay away from touching your a/c system except to power wash
your Condensor Coil routinely.

 

In older a/c systems, the manufacturer used to include a sight glass for
recharging ; you hardly ever see this on systems any more. One would
simply add freon thru the low side until the high side sight glass was
clear of bubbles. Without this sight glass on the system, you must
accurately weigh in the freon charge using an accurate clear Charging
Cylinder with graduation markings on the side ; something that is not
available to the public. To not use this method, is only guessing at
the charge you have put in.

 

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Actually, recharging an automotive AC does require at least EPA 609
certification. USING the kits without such is illegal in the US.

Purchasing R-134a does not require certification since it has many uses
other than as a refrigerant and is not an EPA controlled material.

As stated elsewhere in this thread, 609 is rarely enforced for private
usage.

gerry

 

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Typo above, "R-141a" should read "R-134a"


gerry

 

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Actually, if the system has stood without pressure and a leak, chances
are the hygroscopic PAG or POE oil has been permanently contaminated.
Drain, flush and changing the dryer is the only way to get the acid that
forms when moisture hits the R-134 compatible oils out.

Old R-12 systems used mineral oil that was not affected by moisture.

gerry

 

'Actually, recharging an automotive AC does require at least EPA 609
certification. USING the kits without such is illegal in the US.'

REPLY: I was going to mention this fact, but, R134 is too readily
available to the consumer and abiding by Government Laws is going to be
the least of their concern.

 

'Actually, if the system has stood without pressure and a leak, chances
are the hygroscopic PAG or POE oil has been permanently contaminated.
Drain, flush and changing the dryer is the only way to get the acid that
forms when moisture hits the R-134 compatible oils out.'

REPLY: Correct. And you still need the Vaccuum Pump for pulling a deep
vaccuum once the system is cleaned up .

 

Matt is correct. The proper way is to evacuate the system WITH A VACUUM
PUMP and recharge it with the correct weight of freon. I believe that you
said that the system wouldn't work at all which indicates that the freon
level was so low that the pressure switch was not making. At that point,
you have to assume that the system is empty and probably has air (with
moisture) in it. At that point, you have to use a vacuum. I know I say
that because I'm lucky enough to have one from where I used to work, but I
also know that it's a big outlay of money and you would want a cheaper cure.
I guess you could just recharge it and hope for the best but it won't cool
as well because you won't have the same amount of freon in it, or, if you
put the right amount of freon in it, then you've over charged it with the
air already in there and you could blow hoses, seals, etc.

 

And if it is empty, then it has a leak. One needs to find the leak
before recharging the system. Most DIYers aren't capable of doing that
either. I like working on my car as much as the next guy, but some jobs
just require more tools that I care to buy in order to do the job right.
Most AC work falls into that category.


Matt