I have heard so many stories of bad outcomes with 134a conversions (even by 'pros'). I'm not saying it can't work, just that doing it right is often more complicated than advertised.
It would seem that many outfits are trading on a false public perception that has created something of a 'conversion industry'. Large amounts of money are changing hands, often for the wrong reasons.

Let's face it. There is more money to be made from expensive conversions, and the r12 they reclaim from your system has a market value, so they win twice. If the converted system melts down in a year or two, not their problem...

The cost/benefit analysis is out of whack when expensive retrofitting is done to save $80 on refrigerant. Sure, it will leak over time, but will a topoff every, say, 3-4 years break the bank?

I think part of the perception problem dates back to when the price for r12 was dramatically higher for a time, which may have been partly driven by speculators. Anyways, demand is predictibly down now. 10 years has elapsed, and there are fewer vehicles is operation that use r12. Many of the remainder have been converted. Appliance and industial users have converted.

Fed taxes are around $9 per pound now, and will climb $.45 every year forever, but hopefully the recycled supply will meet the smaller demand, and keep inflation fairly low for years to come, or at least until a better cooling technology is invented...

I used to buy 2 pounds of r12 for a dollar on sale in the '80s. Can you imagine?

__________________
1986 300E 5-Speed 240k mi.

Bottomline with any older Benz is the a/c is mediocre, so you have to keep it up if you live in a warm climate. I have had my 85 380se evacuated and charged once in the last three years and it still doesn't blow ice cold. The first guy I took it to said it leaked and wanted $400 minimum to repair. Second guy, who I trust a lot more said it didn't leak and evacuated and charged it for $120. It's still not ice cold. Luckily, there is an a/c shop in NYC all the taxis use that does the test for free and will do the charge on spec. If the system doesn't hold the charge and blow ice cold, it's free. Wish I knew that last year. When it comes to the remaining r-12, you're at their mercy for the price they charge.

My kingdom for the name/phone # for the NYC shop. Summer's comin' & a have an '87 & '91 300e with a/c that's worthless. Please...& Thanks.
Rich

Good news and bad news?.....

I went to that shop this morning and they did the pressure test and found no leaks. But the system was almost a pound low. So he said he filled and the air was flowing at around 45 F. He said it would blow colder when on the road. Good news is it only cost me $60.

Bad news? ...I said great and then asked some questions about the r12. He told me he uses freeze 12. He says this is compatible with r12 and 134a. I wanted to just stay with the R12, thats what i thought I would be getting.

Two questions:

1. Does anyone know what i should expect from this "freeze 12" stuff? Good cooling? Failing System?

2. Is 45 degrees normal for air conditioning, with vehicle parked?


Thanks,

Josh

That is very unfortunate.

It is illegal to topoff an r-12 system with Freeze-12 (or anything other than r-12, for that matter). The system must be labeled as converted, and fit with the special SNAP Freeze-12 fittings. What you got was probably a full evacuation and recharge with Freeze-12, though $60 sounds low, even for that.

Freeze 12 is an r-134a blend with 80% r-134a, and it is said to be compatible with R-12 mineral oils due to additives. This compatibility is widely disputed, however, and may only really work well with specific types of mineral oil. Many who advocate the stuff still suggest a taking all of the steps one would for a r-134a conversion, including POE oil.

The other big 'claim to fame' is that Freeze-12 provides cooling characteristics more similar to r-12 (superior to r-134a), such that retrofitted systems will not lose their efficiency. This is also widely disputed.

It is said that the cutout pressure should be lower for Freeze-12 as well. The more you dig, the less of a 'drop in' it becomes...

While it is "EPA approved", the EPA SNAP approval process only considers environmental and health factors, not technical performance.

What you needed was a simple 1 pound topoff of r-12, perhaps $30-40 worth of gas.
I would be very unhappy if this happened to me.

__________________
1986 300E 5-Speed 240k mi.

Another problem with Freeze-12 is most A/C shops have Freon Identifiers to make sure the system is actually charged with either R12 or R134A. If impurities are found, most will either refues to service the system, or charge very high prices for the disposal of the contaminated freon. It can not be recycled in either a R12 or R134 equipment.
If one of these impurities is found, I will cost you 200 to 300 just to get the system cleaned out and then the repair and recharge.
My advice is DON'T let anyone put anything in your system except the real thing.

By the way, I get arguments about this, but just to convert a system, I evacuate, replace the dryer (not really necessary for the conversion, only a good practice), Hook up vacuum pump for 1 1/2 to 2 hours, turn off pump for 30 min, check for a leak of the vacuum and if all is OK turn the pump back on for 30 min, and charge with 134 using 85% of the R12 charge and add 2 oz of Ester oil and UV dye.
Did my 84 500 SEL this way 2 years ago, and get plenty of cold air hear NC. Did a friends 87 420 SEL 3 years ago with the same results. Have done many more cars and truck with equel sucess.
There are some GM and Fords which need the pressure cycling switch changed or adjusted, but any car with a real expansion valve doesn't need anything changed. I have had some Chrysler mini vans that cooled to good and I had to over charge them a little to raise the evaporator temperature.
I still believe, if the job is done correctly, almost any system will work just as well on R134 as it will on R12.

Just my $.01

__________________
84 500 SEL (307,xxx miles)

Thanks again everyone for all the help and insight. It is unfortunate that my system is now contaminated. I will label it as such, so no recycling centers will be contaminated. I will also update this thread once we get a really good hot day, and let you all know how the system is holding up.

Thanks everyone.

Best Regards,

Josh