Recharging A/C by yourself or garage

My air conditioner was not cooling anymore. I bought a 134a kit with two
bottles for $35, recharged, and everything seems to be fine.

What is the advantage to having a garage recharge your A/C for around $100
compared with doing it yourself for a fraction of the cost? I know one
thing the garage does is vacuum the lines, is this a necessary step? Is
recharging yourself by adding a can of 134a just a temporary fix?

Thanks.

>Is recharging yourself by adding a can of >134a just a temporary fix?

good question. that is one reason you employ the services of an a-c
shop, to check, and make necessary repairs.

you might do-it-you-self for a while, but eventually the system will
need a through check, before it is crashed by misapplications.

it's a good idea to establish a relationship with an a-c shop, unless
one is qualified to do their own ac work.

>mho
>v fe

"slim" > wrote in message
news:EEXpg.2182$J47.1358@trndny02...
> My air conditioner was not cooling anymore. I bought a 134a kit with two
> bottles for $35, recharged, and everything seems to be fine.
>
> What is the advantage to having a garage recharge your A/C for around $100
> compared with doing it yourself for a fraction of the cost? I know one
> thing the garage does is vacuum the lines, is this a necessary step? Is
> recharging yourself by adding a can of 134a just a temporary fix?
>
> Thanks.

For just topping up a charge, there is no advantage to having a garage do
it. They usually
do NOT put a vacuum pump on the system unless it has been opened up. So you
can save
yourself about $80 of that hundred.

But, if it leaked before, it will leak again. At some point you will have
to fix the leak, or
keep pumping refrigerant into it. A competant mechanic is usually the best
bet to find
and repair a leak.

One of the local mechanics here told me the other day that, to save money on
a family car,
he put in a can of leak sealant and topped the unit up. Car has been
running for three years
now with no further problem.. Generally, the use of sealants is not
advised. But in this
anecdotal case, from a very well trained and competent mechanic, it worked.
(I wouldn't
do it, but some cars may only be worth a cheap fix.)

On Sun, 02 Jul 2006 22:20:20 GMT, "slim"
> wrote:

>My air conditioner was not cooling anymore. I bought a 134a kit with two
>bottles for $35, recharged, and everything seems to be fine.

Sometimes it will be. If it ended up overcharged (very common) that
will take a toll, however. Of course, not every AC that no longer
cools needs to be recharged at all. There are other things that go
wrong!

>What is the advantage to having a garage recharge your A/C for around $100
>compared with doing it yourself for a fraction of the cost?

**Low AND high side pressure is measured.

**Exact amount of refrigerant needed is added -- not by the can

**We evacuate, vacuum and recharge for an exact filll by weight per
manufacturer's specs. Pressure readings are subject to many variables
in their relationship with ounces of refrigerant in the system. This
ensure no air or moisture in the system, we have a record of how
undercharged the system was when it came in. If the manufacturer's
spec is 28 oz that is EXACTLY what it leaves with. Charging by a can
with a low side gauge will probably get you within a half pound but
not reliably any closer. If the car has a clogged expansion
valve/tube and you charge the system by the low side pressure reading
you can easily 2-3 pounds too much in it!

**Leak detection dye added unless already present, system inspected
for leaks and free recheck under ultraviolet light two weeks or so
later.

**Experience with how the particular system should behave and where it
typically leaks..

If the shop does not have a professional approach similar to the above
-- sad to say, many don't -- obviously the advantage is less or none.

Don
www.donsautomotive.com



> I know one
>thing the garage does is vacuum the lines, is this a necessary step? Is
>recharging yourself by adding a can of 134a just a temporary fix?

If the system lost refrigerant and more was added without leak repairs
obviously it is a temporary fix in the strictest sense. Will it last
a reasonable time and be worth doing? Quite possibly so, quite
possibly it will be gone in a month. Without leak checking there is
no way to tell. In any case, the fact is, despite the optimistic
expectations of environmental types, automotive AC systems are
intrinsically less than perfectly sealed from the factory.

>Thanks.
>

"Don" > wrote in message
...
> On Sun, 02 Jul 2006 22:20:20 GMT, "slim"
> > wrote:
>
> >My air conditioner was not cooling anymore. I bought a 134a kit with two
> >bottles for $35, recharged, and everything seems to be fine.
>
> Sometimes it will be. If it ended up overcharged (very common) that
> will take a toll, however. Of course, not every AC that no longer
> cools needs to be recharged at all. There are other things that go
> wrong!
>
> >What is the advantage to having a garage recharge your A/C for around
$100
> >compared with doing it yourself for a fraction of the cost?
>
> **Low AND high side pressure is measured.
>
> **Exact amount of refrigerant needed is added -- not by the can
>
> **We evacuate, vacuum and recharge for an exact filll by weight per
> manufacturer's specs. Pressure readings are subject to many variables
> in their relationship with ounces of refrigerant in the system. This
> ensure no air or moisture in the system, we have a record of how
> undercharged the system was when it came in. If the manufacturer's
> spec is 28 oz that is EXACTLY what it leaves with. Charging by a can
> with a low side gauge will probably get you within a half pound but
> not reliably any closer. If the car has a clogged expansion
> valve/tube and you charge the system by the low side pressure reading
> you can easily 2-3 pounds too much in it!
>
> **Leak detection dye added unless already present, system inspected
> for leaks and free recheck under ultraviolet light two weeks or so
> later.
>
> **Experience with how the particular system should behave and where it
> typically leaks..
>
> If the shop does not have a professional approach similar to the above
> -- sad to say, many don't -- obviously the advantage is less or none.
>
> Don
> www.donsautomotive.com
>

Very good post, Don.
The new equipment for removing refrigerant, measuring it, and replacing it
along with any
needed charge is beyond the reach of most of us, but it is a good piece of
equipment.

The last time I put a charge in mine, I had to replace the Shrader valve,
and the system was
empty when I started (it had leaked down to atmospheric).

This unit requires 2.5 pounds of 134a. I used three full cans (11 oz each)
and then used a
set of precision scales to weigh in the last bit of the charge. It was the
best I could do under
the circumstances, and I could not have been off much. Resulting low side
pressure was
as expected.

The Shrader valve helped, but there is also a leak in the evaporator core,
and it has gotten worse,
so I am going to have to get serious about this.

The fan motor is borderline anyway, so it looks like I either spend a lot of
time under the hood
myself, or take it down to the friendly local independent mechanic. (The
only problem with him
is that he is good, and competent, and therefore has more work than he can
say grace over.)

slim wrote:

> My air conditioner was not cooling anymore. I bought a 134a kit with two
> bottles for $35, recharged, and everything seems to be fine.
>
> What is the advantage to having a garage recharge your A/C for around $100
> compared with doing it yourself for a fraction of the cost?

It will keep working for more than a month.

I know one
> thing the garage does is vacuum the lines, is this a necessary step? Is
> recharging yourself by adding a can of 134a just a temporary fix?

Converting from R-12 to R-134a on most(*) cars works great, IF you flush
the lines to remove all traces of the old oil, use a high-quality POE
oil or double-end-capped PAG oil that won't decompose into abrasive
black goo when exposed to chlorine residues from the R-12, and if you
fix the original leak that the R-12 escaped from, and in some cases make
some changes to the way the system works (such as installing a thermal
compressor cycling switch in place of an EPR valve, or replacing a fixed
orifice tube with a variable expansion valve). Failing to do ANY of the
above will result in a system that may cool great for a day, a week, or
even a few months... but will ultimately destroy itself and have to have
even more expensive work done. Note that you don't HAVE to have a shop
do all that I've described. If you have a vacuum pump (or can rent one)
then you can do the whole conversion at home.

(*) R-134a is less efficient than R-12. Most cars and trucks, especially
older cars from the 60s and 70s, had plenty of excess air conditioner
capacity and can tolerate the loss of some efficiency. But there are a
few cars, usually from the 80s and usually minivans or vans with either
dual AC or a large interior to cool, that were marginal with R-12 and
simply won't cool with R-134a.