Larry, I agree with you. My point was I've been watching R-12 auctions for about 3 weeks. The going rate on ebay seems to be somewhere between $12 and $20 per 12oz. can. My 'luck' was to get 2 cans for $8 each before shipping.

Even at $20 per pound, what sense does it make to convert a system and end up with reduced cooling efficiency? None in my book.

I agree. The sooner the US goes to all metric, the better IMO. AAPAK in Phoenix is selling R-12 for $35/can (12 oz.)

__________________
Dan
1981 240D
1987 300D Turbo
1973 220
Das Beste Oder Nichts

Slugs are slimey things which crawl around in the garden and eat plants...

" AAPAK in Phoenix is selling R-12 for $35/can (12 oz.)"

They are applying the usual 100 percent markup it appears.. better to go to Ebay...

I agree in principle with you! However it is much easier to visualize what a foot or rod is as opposed to a meter. Once you develop the right frame of mind it is much easier to measure and estimate in metric. I developed a very good feel for metrics in Jr high on the science olympiad team and was added to by a year+ of intense aero engineering before I went to computer science in the engineering department.

Several years ago a spacecraft did not enter Mar's orbit properly because of a metric measurement being mixed with english measures. As long as english is the official measure of Aerospace and the U.S. auto industry it will be hard to displace. The A/C system is one of the few places where you will find english measures as the standard in the old benzs. Mostly because they use US components.

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

Someone unloaded around eight cases of 12oz cans...

__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

The changeover to metric has been PAINFUL for those twisting bolts. It's not so bad working on a very old US car or an all metric car. The problem is the US cars of the last 20 years or so. They have both English AND Metric and you have to try about five wrenches on every bolt before you have the right size. What a PITA!

IMHO the only advantage to the Metric system is purely mathematical. If you can do simple math, the English system is just fine especially in these days of calculators. I went through college with a slide rule and a CRC book.

So what if you have odd numbers to deal with like 12 inches in a foot or 16 oz. in a pound, or Temp in C X 1.8 + 32 = Temp in F. You just learn it and go on. If we all grew up on Mars or somewhere with a base 13 number system, we would have just learned and never known the difference.

The Metric system pressure has just been a move toward world government.

Have a great day,

I agree with that sentiment somewhat Larry. But the simplicity of metric math pays off. Especially in international trade. That is the one part of the one world government I would gladly embrace. It is so sad the feds printed up all those metric speed limit signs and they are all sitting in a warehouse. Probably millions of dollars worth. What a waste of money.

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

Hey,
I was just reading this from the 126 manual:
I was charging my AC last night. Started with 37.5lbs of R-12. Put in a charge and weighed in at 34.0lbs. Put the cylinder away and weighed two hours later and had 30.0lbs

From the pressures and sight glass it looks like the system is under charged.
Go figure.

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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Danny, I think you are ignoring the first part of that sentence ....
Did you apply any heat to that vessel containing the R12 ?
When you release R12 from it into your car you will be decreasing its temperature...
You don't want to waste any R12.. so I think you need to check by high and low side pressures and cooling ability... your system can function fine with several ounces less than recommended lbs... compared to any over.
At this point I would ignore the site glass and just use the pressures. But remember the system needs to run at least 15 minutes at proper rpm and load to stabilize... before taking the readings..

If you get hold of the AC manual where they are describing a captured retrieved amount of gas... where they are trying to determine and get rid of any contaminates... it sounds like the same thing... weighing , temperatures, and you have to let the cylinder stabilize before doing the measurements for that process...

EXactly what kind of scales are you using ?

Hey,
Thanks Leathermang. Your comments are always welcome.
I realize what you mentioned to be true. I was just trying to relate what I read in the manual as it relates to the original topic of this thread.

I did let the system stabilize. Long enough to go down the street and through the drive through.
It did appear to be undercharged. None of that matters now anyway. One of the lines at the expansion valve just started leaking. What a PITA this is turning out to be!

I am using a bathroom scale to weigh. It is a fairly good one.

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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"I am using a bathroom scale to weigh. It is a fairly good one."

Not good enough for this job from what you have described...

But just go to pressures and you should be fine... how did you evacuate the system and all that stuff and not find that leak ?

Yeah that's what I figured. I thought I could use the scale just to get a general idea but I guess maybe not.
That's the wierdest part! I pulled 29" vacuum for over an hour. Took it for a test drive after. NO Leaks. Went to the dentist this morning, turned it on and it started hissing.
I couldn't believe it!

I also used Nylog on everything. BTWY I found a substitute for it. Yo can use snot! I swear it's the same thing!

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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(='.'=) This is Bunny. Copy and paste bunny into your
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Among pro a/c repair people, checking for a leak by watching for a falling vacuum is called a "gross leak test." That should tell you something. It will only show up a significant leak.

There are several methods for testing for leaks, but a system should not be considered tight by a gross leak test alone.

Good luck,

Diesel Jim,

Pounds is not a clumbsy measurement for mass, its a unit of force equivalent to the Newton in the Metic system.

F= MA or Force = Mass X Acceleration
WHere:
F is in pounds or Newtons
M is in slugs or kilograms
A is in feet per second squared or meters per second squared

I think you are correct that 1 liquid oz. of water weighs 1 oz. because a pint of water weighs 1 pound on the earth with a mass of 1/32 slug. On the moon the same amount of water would weigh ~1/7 of a pound. But it would still be 1/32 slug.

P E H

So back to the ounces and pounds. My system requires 17 to 19.4 ounces of Freon but my can is 20 ounces. I do not want to overcharge the system. I have a scale and I was thinking of placing the can on the scale, zero it out and then remove some until the scale says I lost .6 ounces or so. Will this work? Is there a better way?