How often does AC need to be recharged?

I can start to notice a slight degradation in the ac. How often does the AC
need to be recharged. I can't find anything in the manual about scheduling
recharges. I have a 2001 Accord EX.

 

I advise you to do it whenever it is obvious that it needs to be
recharged. I once lived in Virginia and did not use the AC during the cold
winter months. I had to have the AC recharged at the end of winter since
my AC no longer produced cold air. Some of the auto related stores such as
NAPA have special thermometers that clip on to the AC vent.
Jason

 

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Just changing the cabin filters will make a huge difference. I do them
at least yearly. But if it's not that, I can't say.

'Curly'

 

With the older R-12 systems, it was recommended to run the AC at least once
every week for about 10 minutes throughout the year just to keep the seals
lubricated and protect them from drying out. I don't know if this
recommendation still holds true for the R-134a systems.

Eric

 

It theoretically should never need to be recharged. In practice, systems
start leaking eventually and do need a recharge, but a 2001 is a little new
for that. I figure at the ten year mark about half of A/C systems have
needed recharge.

If your A/C is getting weak, you can change the cabin filter as Curly
recommends. If it has been changed recently it's time to schedule a checkup
with an A/C professional. In the R-12 days you could do almost everything
yourself, but R-134a is a very diffferent beast. I don't know why, but I had
no trouble recharging R-12 systems and failed miserably the time I tried to
recharge an R-134a system. Worse, regulations have made the overhead very
high for professionals. That means you can expect to part with most of $100
US for a check-up, which involves emptying the system by filtering and
capturing the refrigerant then refilling with the measured amount of R-134a.
A check of the operation, along with fixing or identifying air flow and
control problems completes the job.

To rub salt in the wound, a decade after the ratification of the Montreal
Protocol - which included banning the production and mandating other
controls for R-12 and other CFCs - A NASA/NOAA mission called POLARIS
determined CFCs (in fact, all halogens combined) have only a minor effect on
stratospheric ozone depletion. The main culprit is reactive nitrogen oxides,
formed by sunlight. Isn't that special?

Mike

 

but it was a great business opportunity! from what i understand, r-12
was out of patent, made by many companies and competitively priced.
r-134a otoh...

 

Michael Pardee says...

I have a 94 Accord, which I think was the first year of
134a. It isn't so cool now, and cycles frequently. I was
planning to get a can of 134a at Wal-Mart, and the
connector/hose, and just charge that into the low side like
I used to do with R12 systems. Are you saying that doesn't
work? If so, I sure would like to find out why.

If you're saying they have to evacuate all the old
refrigerant, and add back the correct amount, rather than
just adding more in the first place, I wonder if this is
"regulations" or just the standard repair scam bullshit.

I sure would like to get an explanation, in scientific
terms, of why you can't just add a little 134a. Do pressure
gauges not work with 134a? Do they not tell you whether the
charge is correct?

 

I don't know why it is so, but even with plenty of experience with R-12 and
a guage and thermometer I was unable to find the correct charge for my son's
Acura. It turned out the correct charge was about half the bottle. When we
were done I could hear liquid drops hitting the compressor so I told him to
leave it off until he got it done right. I didn't want to ruin his
compressor.

We added gas slowly and I watched the pressure and vent temperature, but it
never was anywhere near correct until it was done by weight. I can only
guess the lag time in the system is very long compared to the half minute or
so it takes R-12 to stabilize. A friend who went into refrigeration before
he moved away told me that with R-134a the condensor pressure is more
critical than it is with R-12... that may be why it can't be done by ear any
more. If the condensor has to stabilize to evaluate the state of charge it
could take hours to do it "by ear." But that's only a guess to explain my
failure.

Mike

 

A can of R-134a contains both refrigerant and lubricating oil, and I have
read that the practice of charging without purging can, over time, result in
significant accumulations of excess oil, giving rise to unusually high
operating pressure and leading to premature seal failure.

 

Michael Pardee says...

Thanks. But I still think we need to find an authoritative
technical explanation.

 

Please let us know what you find. It's always good to know these things.

Mike

 

A can of R-134a contains both refrigerant and lubricating oil, and I have

$920 later I just found this out. I had a small leak that only happened when
the unit wasnt used for a week or more. I added oil and a recharge can of
134a and my compressor locked up a month later. Was real cold for a month
though! Mechanic told me the same thing, too much oil and shouldnt be done
by shadetree mechanics wiythout meters.

 

Ow! That lesson was a dear one! I do know that overcharging any A/C sysem
will cause liquid to overflow the evaporator and "slug" the compressor. Very
bad news.

Mike