Tony K

Find someone who has one and borrow it . . . . .

A vacuum pump is to all cars what 9201 is to 944s; it pays for itself in 1 or 2 uses, and is valuable thereafter. . . .

Porsche-O-Phile

I'd actually do that; I've asked around a little bit about vaccum pumps but nobody seems to carry them. I already have a manifold / gauge / hoses (good one, about $150) and some other stuff. I did see a little "box" that runs off an air compressor on the Freeze-12 website (under "store") that's like $40 or so. Dunno if this would even help or what though - there's no gauges or anything. I don't even have an air compressor right now. Only thing I have is my little hand vaccum pump - better than nothin'. I used it to put a test vaccum on my 951s system to check for any obvious leakage; it held 20 psi for an hour or so - I guess that's adequate, but that pump is really not that good for sucking old oil / freon out from the whole system - I'd need a good power pump for that.

jim302

There are no OEMS that I know of that use ester oils.
PAG is the oil of choice if you are doing a complete change over.
Ester is pure garbage and has caused me four returns so I stopped using it.

I have converted many systems over professionally.

There is a lot of good advice in this column on how to do it right.

Now for the wrong way;
Five years ago I grabbed a low side adapter (available at Maney, Moe, and Jack’s)
I filled it with R134 until the bubbles stopped in the sight glass.
I intended on leak checking the system, evacuating, repair the leak, change the oil to PAG, and refill with 134.
Two years later I topped the system off and again this year.

If you get into any oils, I recommend flushing the system and using PAG.

TrevorW

Today in my world environments class the topic of CFCs and R-12 vs R-134 came up today. According to my professor R-12 is non-toxic and non-corrosive where as R-134 is corrosive and toxic. So is the only reason why R-12 is so hard to get because of the CFCs? As an interesting side note, in 1996 more R-12 was smuggled into the U.S. from Mexico that all drugs combined.

Tony K

Jim,

Tell me more about why PAG instead of ester. Any comparison of their physical or chemical properties? Details of what went bad because of ester, how, etc?

Thanks,

Tony

KuHL 951

I've used a $14 Vac pump from Harbor Freight on 3 cars now. It runs off of a standard air compressor and will pull up to 29 Hg. I only use it on cars that are already completely depleted and I'm doing seals/dryer anyway so don't bag on me about the Ozone Hole please. It paid for it self in the 1st 15 minutes I owned it since I get my Dupont R-12 from Mexico at a very good price. Will it last forever? I doubt it but it does work to pull everything out before recharging.

Randy_J

http://www.harborfreight.com/cpi/cta...emnumber=92475

"Venturi-type vacuum pump removes moisture from air conditioning systems so can you safely add refrigerant. Easy to operate, just connect an air line and it pulls full vacuum within 2 minutes. Ideal for automotive air conditioners, home air conditioners, refrigerators, freezers, and more!
Includes 1/2" ACME (R134a) connector.
Vacuum level: 28.3" of mercury at sea level
Air consumption: 4.2 CFM
Air inlet: 1/4'' NPT"

Is that the one you are using?? Would seem to be the right tool for the job!

triscadek

Story has it that DuPonts patent expired on R-12 just about the time it was discovered to be so dangerous and basically banned.

I've been told that the USAF still uses large quantities of R-12 as a spray on parts cleaner. They must know how to use it correctly.

KuHL 951

That's the one...mines red and had R-12 connectors but you can by the R-134a adapters at any NAPA store to convert it if you need to. I was amazed, it worked great. It helps to have the manifold set to make sure the AC system holds vacuum after you are done. I run it for about 1/2 hour.

Yabo

So it would seem (from tony k's responses and the cheap pump) that I could do my whole AC (assuming no leaks) with a 16 dollar pump, some r134, and some esther oil? Sounds like its worth a shot if nothing else....

Porsche-O-Phile

Thanks for the link. I'll have to get an air compressor I guess (*sigh*, one more thing taking up space in the garage) but I agree it will be worth it.

dochranilovich

I bought a Quest R-134a RETROFIT & RECHARGE KIT made to convert R-12 to R-134a for, I believe, $25 marked down from $41 at my local Meijer store. (Like a Wal-Mart, except based in MI, and allegedly the first of the so-called super-store chains.). I've seen the same kit on the Internet on sportsmansguide.com for $32 or so, and at my local auto parts store for either $30 or $40, depending on whether or not it was on sale.

It came with high and low-side retrofit fittings and caps, three cans of 134a refrigerant, a can of Retrofit Oil with conversion additives that allows the existing mineral oil to remain in the system, and a recharge hose with quick-connect and can tap. Quoting the packaging, "the Retrofit Oil contains PAG oil -- the lubricant approved by the original equipmont manufacturers that allows the existing mineral oil and the PAG oil to be compatible so the mineral oil does not need to be removed and contains conditioners that stop leaks and rejuvenate o-rings and gaskets."

Step one is to remove remaining R-12 with approved equipment, which Williams AutoWorld did when my A/C was found to have a leak in the condenser. I was quoted $1,200 to replace and update the A/C, which I declined to have done.

Mid-America Motorworks has an "Upgrade to an R134A-Ready A/C compressor system" kit for '83-'95 944-968, item 412-085, for $599.99, for the do-it-yourself types. I'll try my kit first, though.

Zero10

I always wondered how well the venturi vacuum pumps would work. Good to know that they work well. I think I'll pick one up. The only catch is you need a rather significant volume of compressed air for it to work, or at least that's what I was told, but it should be just as fast or faster than a vacuum pump.

KuHL 951

I have a so-so 5.5 HP single-stage compressor that does 5.5 cfm @ 90 psi and 6.9 @ 40 psi. It is way more than adequate for running this type of vac pump. Once vac is pulled, it barely cycles unless the AC system leaks like a sieve but it still pulls enough to get any crud and oils out.

jim302

Chemical makeup, specific gravity, or atomic chart on it I cannot help you. I will tell you what I have seen and what works for me.

The reason a lot of conversion places use ester is because it is supposed to mix with the mineral oil remaining in the system. In every case I used it, the “mixture” turned grey. Clear and brown don’t make grey in my color chart. Two cases the mixture gummed up and only clogged the expansion valve. I also had two cases of catastrophic failure because of the crappy gunk.

I will not say it does not work. There are a lot of conversions I did with ester that a still blowing cool today.

If I have to open a system up to convert it, I flush the system and only use PAG now.