Air Conditioner r12 - r124a Conversion Catch-22 - Page 3 - Mercedes-Benz Forum
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post #21 of 27 (permalink) Old 05-21-2016, 11:32 AM Thread Starter
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Originally Posted by innovation560 View Post
I am fascinated by this 134 vs 12 discussion. .

Since this thread has garnered some interest and summer is approaching, I wanted to add a link to the EPA's statement on r12 conversions and their opinion on OEM retrofit vs. Least-cost Aftermarket retrofit. See post #4.

What is a reasonable price for A/C R12 to R134 - Ford Mustang Forum


This is all very basic info to orient a newcomer to the issues we're discussing here. I wish I had found this when I first started my search weeks ago because it is a simple nuts-and-bolts explanation and it would have saved me a lot of reading.

Apologies for posting an outside forum link - I hope that is kosher here. The info is a little old and the EPA has taken it off their website (to make room for the next conversion - r134 is gone in 5 years!). I felt it was too long to copy/paste deep in this thread, so I'm providing the link for anyone curious about some of the basics.
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post #22 of 27 (permalink) Old 05-21-2016, 02:44 PM
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Thanks. I've considered it - every auto store around me has the cans and valve adapters. Did you do anything about the lubrication?

Do you think the gauge on the can gave you an accurate reading when using the valve adapters? I know that over-filling the system with too much r134 also causes failure, so I'm concerned with over-filling if I use that method.
There have been cases where I overfilled. You will hear the clutch engage and disengage, cycling on and off as you overfill. If the weather is not very hot then and no law enforcement around you can press the valve like that in your tire to let some out until it stops cycling. This will get you the coldest results. The first time I filled while it was super hot outside. Then just fill until it gets really cold.

There is no real reason for the tech to lie to you about the conversion. You are not the owner that had it done and many warranties have a disclaimer for original owner only.

(I'd take my chances if I didn't have the money. I still have the receipt for my conversion back on 06/05/03 for $1690. They charged 6 hours of labor, a total of $570. The current labor rate when I last spoke to someone with a Rusnak shirt was $175/hr....)
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post #23 of 27 (permalink) Old 05-21-2016, 02:54 PM
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Originally Posted by djsjjd View Post
Thanks. I've considered it - every auto store around me has the cans and valve adapters. Did you do anything about the lubrication?

Do you think the gauge on the can gave you an accurate reading when using the valve adapters? I know that over-filling the system with too much r134 also causes failure, so I'm concerned with over-filling if I use that method.
The cans come with a proportionate amount of lubrication, so all I did was add until it was cold. I got greedy and followed the instructions to keep adding per the gauge. The compressor clutch will cycle on off on off as you overfill. If no law enforcement around press the valve like a tire valve and let out some until it stops cycling. In very hot weather just add until it comes out nice and cold. Mediocre output most likely means it is low. If it is not hot, add until you notice the cycling and release some until the cycling stops and then immediately stop. It may start to cycle again, then release some until it stops. (It is not pleasant working in extreme heat, so last time that is what I did). Very happy with the A/C Pro....


Oops, sorry for the sort of double post! AutoGuide wasn't displaying my original one.

Last edited by jzchen; 05-21-2016 at 02:57 PM.
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post #24 of 27 (permalink) Old 05-23-2016, 04:39 PM
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In town (New Orleans) 100F degree day... approximate vent temp tooling around town @ 44F - 46F (Highway Sub 40F).

With 44MM condensers and Maradyne M142K Champion Aux Fans

84D w/Sanden compressor 2F-5F rise in vent temp @ long stop light... or, a few quick successive stop signs (the Sanden does cool quicker and hold temp longer... although, the R4 does get as cool as the Sanden).

85TD w/Harrison (R4) compressor 5F-9F rise in vent temp @ long stop light... or, a few quick successive stop signs.
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post #25 of 27 (permalink) Old 05-23-2016, 06:01 PM
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I just read most of your A/C posts, impressive.

After all your work, what would you say is the best set up:

A. Convert to Sanden A/C compressor and condenser upgrade kit plus Maradyne fan- run a blend of R12 & R134.

B. Same as A. but straight R134

C. Leave the current R4 in place or purchase a new R4 if faulty, new OEM condenser add a Maradyne fan and run R12 gas.

D. Same as C. But purchase Sanden A/C compressor.

Thanks
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post #26 of 27 (permalink) Old 05-23-2016, 08:47 PM
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Let's get *Blends* out of the way first...

I have the manifold gauges and a vacuum pump... so, I do all my own A/C work. Here is one of *many* *many* links on Blends.

http://www.968forums.com/topic/905-m...-refrigerants/

Firstly, what are *blends*? They are, in general ...a combination of propane and iso butane. There are many on the market... I use, Envirosafe R134a Replacement. I understand its physical reactive properties and I understand it chemically. I have *never* found a single documented failure of the product.

Next, it can be used without evacuating the system... whether that system is R12 or R134a, i.e., it works with both lubricants and is highly tolerant of moisture. That said, if there was a system failure as in the compressor imploding I would certainly evacuate (flush & vacuum) the system.

So, let's say ones system isn't working properly because it is out of refrigerant (R12 or R134a). Jump the Low Pressure Switch to see if the compressor engages. If yes, you can easily convert an R12 system to R134a (about 15.00). Then use a tap/recharge hose with gauge (as pictured) to add one (1) to two (2) oz of lubricant... then, add the blend (about nine (9) to twelve (12) ounces) using the same tap and gauge. The refrigerant should have dye in it so that you can trace leaks. Again, the system need not be evacuated when using a blend.

So, you can test and possibly have a working system for under 100.00.

NEVER< >EVER< >EVER... USE A STOP LEAK!!!!

You can also do this if your system is already R134a by using R134a with dye to see if the system works and to trace leaks. However, R134a like R12 are far more sensitive to moisture... so, they should be evacuated to get the moisture out. Remember R12 is environmentally unfriendly and so is R134a (it also causing testicular cancer) Blends are environmentally benign. I would also add that blends create *far* less head pressure on the high end putting far less stress on the entire system.

I am *not* recommending blends here... It is just what I do.
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'84 300D 176k
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Last edited by dennislarock; 05-23-2016 at 09:05 PM.
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post #27 of 27 (permalink) Old 06-23-2016, 12:18 PM Thread Starter
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Time for the final update. I did a lot of shopping for the different options discussed in this thread and didn't find anything I liked or trusted, so nothing has been done.

After some research, I quickly abandoned the idea of finding a shop in Tijuana (where r12 is legal). Too many risks going in cold as a gringo with no contacts there.

Even though I was told by countless shops that "r12 is still legal, it just costs $110/lb and I no longer will touch it," I couldn't find a shop that actually sold it. Half the a/c shops told me it was illegal, the other half told me the quote above, yet I couldn't find a shop that still works on r12. So, I abandoned the idea of trying to fill it with r12. (Even if I found a shop that had it, the car requires 2.6 lbs of r12, which would have been expensive.)

I don't like the idea of spraying r134 cans from autozone into my r12 system, so I didn't even try. I also have not attempted to change out the temperature regulator ($40-$50 part, iirc) which I read in the forums might be the easiest fix since the compressor and everything else is working..

With a heavy heart, I've decided the best thing for me to do is sell the car. I have a couple of big road trips planned that will take me cross-country and back over the next 6 months. Even if I fixed the a/c, there is no getting around the gearing in these cars that is more suited to 60 mph than the 80+ mph I'll be travelling on interstates over 8 hours/day. I'm "buying" a Lexus LS from my grandmother that is in great shape and much better suited for the type of driving I need to do. I live in an apt. with on-street parking and can't keep a 2nd car around. : So, it doesn't make sense for me to keep it as much as I'd like to.

I'm off to a family wedding/reunion this weekend and will be listing it locally in SoCal on Craigslist, etc. next week when I get back. If anyone is interested in the details, let me know and I'll send you the listing & pics.

Other than the a/c issue, it's a great car. 1-owner car for first 30 years in SoCal until he passed away, Maint. recs from MB dealership. Next owner put in $11,000+ to upgrade all wear items like bushings, engine mounts & front suspension & vacuum system. Have all receipts.(He sold because he and his Swedish wife moved to her home unexpectedly - he was obviously planning to keep the car - a look underneath will confirm the amount of work he did) New front brakes, brake pads on all 4, Hella headlights, oil cooler hoses, valve adjustment and diesel purge done by me. Runs amazingly well. Everything works: all windows, sunroof, cruise control, door locks. Very clean California car.
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