How To Recharge A/C

I bought a dozen new bottles of R-12 air conditioner refrigerant, for a dollar a piece at a yard sale. It's been years since I recharged my truck a/c. Can anyone step me through doing it? Seems like I ran the engine, then I unscrewed the deal on the low pressure side. Now, I can't even remember how I would know which one was the high and the low pressure side.
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MilkyWhy wrote: I bought a dozen new bottles of R-12 air conditioner refrigerant, for a dollar a piece at a yard sale. It's been years since I recharged my truck a/c. Can anyone step me through doing it? Seems like I ran the engine, then I unscrewed the deal on the low pressure side. Now, I can't even remember how I would know which one was the high and the low pressure side.
See this website, it should help in understanding what is involved with CFC-12 refrigerant evacuation/recharge.
http://www.epa.gov/ozone/title6/609/justfax.html
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The best advice I have seen out of all of these: Sell the small cans on Ebay, and have a shop do the job for you. The last I saw small cans, they were going for $20 each, and that was several years ago. Sell them in the spring when it's warming up, no one hardly looks for freon in the fall or winter.
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Been awhile but it goes something like this.... Low pressure side of compressor comes from your under dash evaporator, the compressor shoves that vapor into your condenser( front of radiator), then liquid flows back to a receiver drier with a sight gauge on top or nearby hopefully so you can watch for bubble stream to go away when you add that R12 to the low side of compressor, the liquid then gets metered by a small orifice back into the evaporator. Put too mux r12 in and you mux compressor or blow a hose that hits you in the eye while freezing your tongue solid which breaks and falls off as soon as you try to curse.
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MilkyWhy wrote:

And do you know if it needs to be recharged? I suspect someone asking that question has not really determined a charge is needed, and or done any other work that might be needed before recharging.
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snipped-for-privacy@wmconnect.com (MilkyWhy) wrote in message

If you plug the can into the high pressure end, it'll explode in your hand like a hand grenade.
Use your other, still functioning hand, to screw another can into the low pressure end. You should know which is which by now.
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Trade a regular car A/C tech a new can for checking your charge. It's a fair deal.
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Someone named snipped-for-privacy@gmail.com (Yaofeng) Proclaimed on 22 Sep 2004 05:49:37 -0700,

no it won't. It's impossible to get the fittings messed up.
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(Yaofeng) Proclaimed on 22 Sep

Maybe not with your 2004 R134a system. This guy has the good ole hole in the sky r-12. May be you are too young to remember?
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On 23 Sep 2004 05:26:59 -0700, snipped-for-privacy@gmail.com (Yaofeng) wrote:

Maybe your too old and forgot? Even R12 used different sized fitting for high and low pressure on everything after the mid 70's.
Steve B.
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(Yaofeng) wrote:

Old maybe, but not demented.
The use of different size fittings was not universal. I had a 1983 Nissan Stanza which has identical fittings. I used to charge it myself with R-12 at a buck a can. Being young and stupid, I remember connecting the can to the high pressure fitting at one time. Luckily it did not explode because the compressor was not putting out sufficiently high enough pressure to make it a hand grenade.
Why do you think car manufacturers change the fitting size? It did not become universal because cases of refrigerant explosion did not stand up in court.
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G. Morgan wrote:

If you don't know what you are talking about Mr. Morgan, keep your mouth shut or you're liable to cause someone to get someone hurt.
The OP did say "R-12" and older vehicles (Which include most of the ones which used R-12.) had identical fittings on both the low and high pressure sides.
I've still got my refrigeration gage set, circa 1980, which testifies to that.
Jeff
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I also have the adapter for my guage set that I had to use on on the high side of my 80s and early 90s R12 cars. It was smaller..
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Greg wrote:

Me too.
I suppose I came on too strong on Mr. Morgan, but the OP implied that his truck was OLD and many trucks have a way of staying on the road far longer than most cars do, so it could well have had equal sized fittings.
With insufficient information to go on, Mr. Morgan should have at least qualified his post.
Cheers,
Jeff
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There are some excellent forums at www.aircondition.com.
Basically you need to:
1. Hook up manifold guages and understand you system's current performance. (high pressure, low pressure, ambient temp, RH, and AC's output temp.) Compare this with the manufacturer's performance charts. 2. If the system is low on refrigerent you need to find and fix the leak and any failed components and make sure the system has adequate refrigerent oil. You should also replace the expansion valve and accumulator anytime the system has been opened. 3. Now you have to recovery any existing refrigerent and then pull about 29" of vacuum for a min. of 30 minutes to boil out any moisture in the system. 4. Now you can recharge the system by adding the exact weight of refrigerent recommended by the manufacturer.
AC work is very exacting.
If you're not committed to do the job properly, I'd suggest you "hawk" the R-12 on Ebay and pay a professional to fix your AC.
snipped-for-privacy@wmconnect.com (MilkyWhy) wrote in message

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snipped-for-privacy@gmail.com (davefr) wrote in message

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It might vary with manufacturers, but according to GM the valve should be inspected and cleaned. (especially if you've had compressor failure). However new ones are only a couple bucks so it's better to just replace them.
On my GTP it's right below the master cylinder in the liquid refrigerent line and pretty easy to replace.
snipped-for-privacy@optonline.net (Chet Hayes) wrote in message

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MilkyWhy wrote:

fittings. The cap on the fitting of the tube going into the radiator cooler has an 'L' on it, and the fitting on the tube going into the firewall has an 'H' on the fitting cap. It has never been serviced, so I would assume that the caps were not misplaced.
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On 22 Sep 2004 06:22:22 GMT, snipped-for-privacy@wmconnect.com (MilkyWhy) wrote:

Check the shrader(sp) valve and see if you still have pressure. If not you need to evacuate with a vacuum pump. Also, on a cool day, you may need to jumper your low pressure cut off switch to get the clutch to engage. Or else put the R-12 in a pan of hot water.
Pj
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MilkyWhy wrote:

Whatever you do, don't ask that question on alt.hvac. Those guys will chew you up and spit you out.<G>
Jeff
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