buy some r12 or convert to 134a? - Page 2 - PeachParts Mercedes-Benz Forum

Cr from Texas · #16 04-25-2009, 11:23 PM

Quote:

Originally Posted by leathermang

It is four ounces which is allowed by the EPA of the R22...

You may can add all of it without turning on the compressor... but it might take a long time....and almost certainly would need the help of warm water under the can... if you are up to pressure you do not need to jump the switch....

Thanks, I stand corrected on the amount and my intent was to sent the OP to the archieves to find the details.

I'm filling from a 30 lb (about half full) cylinder setting on a scale. I think the cylinder will have enough pressure to push the required amount into the system. From cans, I can see it being a slow process as the can pressure would drop quickly.

leathermang · #17 04-25-2009, 11:32 PM

I tell someone almost daily about the four ounces and nitrogen to test for leaks... easily the best way...

I think many places fill in liquid form.... but one would need to be very careful as to where the charge valve was located in doing that... that way the residual pressure is pushing the liquid in... much faster...
Back in the early 1970's I charged in liquid form on one car.... had to take back two brand new compressors due to cracked valves.... EEEEKKKKK !!!!!!!
I also accidentally hooked up to the high side once.... and luckily felt of the can... it was hot and I could have lost my eyesight from an explosion... since then I follow all the rules... did not know the rules back then...

lietuviai · #18 04-26-2009, 12:06 AM

I found my R12 on CL last year. The seller had 8 cans of the stuff and I bought all of them from him. I think I only paid $60 for them.

leathermang · #19 04-26-2009, 12:21 AM

I don't know why it is that so many people try to make it sound like R12 is prohibitively expensive... but they regularly do... maybe they are trying to keep the competition down by scaring people from even checking on the prices... Now, if you walk into a local parts store with your license and ask for a can.... YES.... way too high a cost...
If one does it right... seals up everything... it does not take much R12 and it should last for 6-8 years before needing servicing....

compress ignite · #20 04-26-2009, 01:48 AM

In no particular order

Doubly Flushed System
BG's FrigiQuiet
New Receiver/Dryer
New O-Rings WITH NYLOG
New R-12 Compressor
New Parallel Flow Condenser
R-12 Refrigerant (BY WEIGHT)
Nitrogen Pressure Test
24 Hr Vacuum test.

('Be Able to Make Ice Cubes on the "Hat Rack".)

leathermang · #21 04-26-2009, 10:17 AM

Those are solid actions Compress Ignite... Your system ought to be ' good to go' for a long time...

I would add that sometimes depending on the trash in the system the TXValve may need to be replaced also.

Matt L · #22 04-26-2009, 01:44 PM

Quote:

Originally Posted by Cr from Texas

Thanks, I stand corrected on the amount and my intent was to sent the OP to the archieves to find the details.

I'm filling from a 30 lb (about half full) cylinder setting on a scale. I think the cylinder will have enough pressure to push the required amount into the system. From cans, I can see it being a slow process as the can pressure would drop quickly.

Pressure isn't the problem. If the car and the cylinder are the same temperature, they will also have the same pressure (assuming absence of air or other contaminants).

The problem is that putting refrigerant into the car involves moving heat. If the cylinder is upright, you need to boil refrigerant in the can and condense it in the car. It takes energy to move heat (otherwise we wouldn't be having this discussion at all!). That energy can be supplied by heating the tank, or by lowering the pressure in the suction line by running the compressor. Or even by having the tank at a higher level than the car so gravity can give you the energy (actually, it's you lifting the tank), but that will take forever. I mean, probably days.

I have a Robinair heated Dial-A-Charge, and it works great. Getting the refrigerant into the charging cylinder still takes some heat. Even a hair dryer aimed at the inverted tank gets the cylinder filled in just a few minutes.

leathermang · #23 04-26-2009, 05:56 PM

Quote:

Originally Posted by Matt L

Pressure isn't the problem. If the car and the cylinder are the same temperature, they will also have the same pressure (assuming absence of air or other contaminants)....

I have a Robinair heated Dial-A-Charge, and it works great. Getting the refrigerant into the charging cylinder still takes some heat.

It might be a little more dynamic than that... we assume the car system to have been vacuumed... and as soon as you open that valve on the refrigerant the can starts to cool... so the first helps get it into the car...but the second works against it... so that heat properly applied is really helpful...
This is assuming the compressor has not kicked in yet...

Mark DiSilvestro · #24 04-26-2009, 10:49 PM

Last Summer, I decided to see if I could get the AC working on my '82 240D. One of the PO's teenagers had been in a fender-bender at one time, and sheared off the condenser tubes, so the system had been open to the elements for several years. I got a used condenser, new filter/drier and decided to try an R134 conversion because the operating condition of the rest of my system, including the rebuilt R4 compressor was unknown. I didn't want to sacrifice my remaining stock of R12 if there was another leak or a bad compressor. Yes, I hear that R12 can be found fairly cheap on places like eBay, but I'm not willing to gamble on unknowwn sellers, and last time I checked, my local Pep-Boys was asking about $95 for the 12 oz. cans! So I repaired the compressor mounting, then flushed the used condenser, installed the new filter/drier, and one of those R134 conversion kits from WalMart. Vaccumed, added 3 oz. oil and the R134.
Found the system cooled a bit weak and the compressor was noisy, but I could live with it.
Today it got over 90F and my system was low enough on freon for the compressor to not engage, so I added two more cans of R134. As there must be another leak, I'm glad I didn't waste my R12. Need to save that for the AC on my '84 Euro 300TD, which is still cooling very well on R12.
Meanwhile I'll try to find the leak in the 240D, but if it's in the evaporator, I'm not pulling the dash to fix it. (This was a $225 car!)
Incidentally, I didn't need to jumper the pressure switch. After adding the first half can there was enough pressure to get the compressor clutch going.

Happy Motoring, Mark

leathermang · #25 04-26-2009, 11:15 PM

About trusting the R12.... I assume you are talking about a bulk container...
I bought mine on Ebay in the 12 oz cans.... not much to go wrong there.... this was several years ago and I think it came out to $18 per can delivered...