AC? - PeachParts Mercedes-Benz Forum

subman60 · #1 06-30-2014, 06:07 PM

I have an 82 240D. It was converted to R134A by the 1st owner (I'm the 3rd). He had the work done by a MB dealer, there is a tag under the hood that gives this information. I know the AC systems are marginal in these cars but what kind of temp can I expect to get out of the center supply vents? Checked it today outside temp of 80deg feel like temp 102deg. The best she would do was 77deg this was while being driven. Sitting in the driveway it was 85deg.

Thanks ahead of time for your help.

Mark

Phillytwotank · #2 06-30-2014, 06:15 PM

They don't work very well on r134 but I think you should see little better than 77° If everything is functioning properly

subman60 · #3 06-30-2014, 06:27 PM

I wonder how much trouble it would be to switch back to R12. How hard is R12 to get now?

engatwork · #4 06-30-2014, 06:32 PM

Get the permit and purchase it off ebay. Do a search and you can read all about it. You won't go wrong going back to 12.

sleepstar · #5 06-30-2014, 06:42 PM

R12 is easy to get because demand has eased tremendously since production was phased out. shop around for the best place to take the certification test. i believe mine was $20 and it was instantly graded. you can then buy R12 for about $20-40 per can including shipping, depending usually on the brand (real dupont freon seems to fetch a slightly higher price)

subman60 · #6 06-30-2014, 06:58 PM

I think I know the process to switch it back over but could someone who has has worked on AC systems recently please give the steps. Does the oil need to be changed or is the oil in the system comparable with R12. Also I would guess a vac would need to be pulled on the system. I used to work for an HVAC wholesaler but that's been over 10 years ago. I don't remember much, hell getting old. Plus I am sure a lot of rules have changed since then.

Phillytwotank · #7 06-30-2014, 07:09 PM

Or you could go with the ES12 from enviro safe. No license required so it's easy to get, comparable with all oils, super inexpensive and it works almost as well as r12. Certainly works better than r134a in a w123.

TheDon · #8 06-30-2014, 08:46 PM

Quote:

Originally Posted by Phillytwotank

Or you could go with the ES12 from enviro safe. No license required so it's easy to get, comparable with all oils, super inexpensive and it works almost as well as r12. Certainly works better than r134a in a w123.

I bought some of that stuff and sadly I didn't get to test it out due to the system not sealing well.

ROLLGUY · #9 06-30-2014, 09:45 PM

Quote:

Originally Posted by subman60

I have an 82 240D. It was converted to R134A by the 1st owner (I'm the 3rd). He had the work done by a MB dealer, there is a tag under the hood that gives this information. I know the AC systems are marginal in these cars but what kind of temp can I expect to get out of the center supply vents? Checked it today outside temp of 80deg feel like temp 102deg. The best she would do was 77deg this was while being driven. Sitting in the driveway it was 85deg.

Thanks ahead of time for your help.

Mark

You have to start at the beginning. Is the system fully charged? If you think not, you could have a leak somewhere. It is best to check for leaks before any charging of the system is done. If you have a leak, FIX IT! Once you are sure there is no leaks in the entire system, then you can start from scratch. Recover the remaining refrigerant, pull a vacuum and dispense the proper amount of refrigerant for the system. The red tag on the core support states the proper amount. Should be 2.2 pounds of R12, or 80% of that amount of 134a. The sight glass is useless if you charge with 134a, perfect for R12. In fact, we just did an R12 recharge the other day. The tech put in exactly 2 pounds and still had a few bubbles. He put in exactly .2 more and the bubbles went away (looks like the MB engineers got something right

). There may be other reasons for those high vent temps, but most likely it is low on refrigerant. You need to also look at the pressures. There is no way to tell the condition of the system without knowing the pressures, and if they are within spec. Of course I would suggest you ditching the stock GM R4 compressor, and installing a Sanden. The R4 will eventually fail, and not good ones are available. Besides being a bad design, they are not as efficient as a Sanden style (axial piston- wobble plate design) compressor. The R4 depends on the oil circulating with the refrigerant to lubricate ALL of it's internals. The Sanden style has it's own oil sump along with a small amount of oil in the refrigerant to lube the cylinders. It is a much better, longer lasting, quieter and smoother design than the R4 (radial, 4 piston). There you have it- your A/C education for the day......Rich

TheDon · #10 06-30-2014, 09:51 PM

^----

This guy knows his stuff, take his advice and buy a sanden kit.

There is discussion(well my thread) on pressure testing since apparently pulling a vacuum and checking for leaks is not the way to go.

ROLLGUY · #11 06-30-2014, 09:53 PM

Quote:

Originally Posted by Phillytwotank

Or you could go with the ES12 from enviro safe. No license required so it's easy to get, comparable with all oils, super inexpensive and it works almost as well as r12. Certainly works better than r134a in a w123.

The only (well maybe not the only) problem with refrigerants other than R12 or R134a, is that no reputable shop will recover the refrigerant after testing if anything but R12 or R134a is found in the system. Yes you could bring it back after the system has been emptied (some have had the contents of their system "mysteriously" leak out), and they will work on it. Most shops do not want their refrigerant supply contaminated. I say most, as the reputable shops will hook up a gas analyzer before recovering any refrigerant to be sure of what they are recovering. They don't want to put R12 in their 134a tanks, and visa-versa....Rich

ROLLGUY · #12 06-30-2014, 10:03 PM

Quote:

Originally Posted by TheDon

^----

This guy knows his stuff, take his advice and buy a sanden kit.

There is discussion(well my thread) on pressure testing since apparently pulling a vacuum and checking for leaks is not the way to go.

The seals in the compressor are made to keep the pressure in, not out. Yes they will hold a vacuum, but that is the worst way to check for leaks. Since the system is under pressure, you need pressure to test for leaks. When I am relatively sure there is no leaks, I charge the system with the proper amount of refrigerant and oil (UV dye as well). I then use 3 methods for checking for leaks. 1) spray bottle with soap and water, then 2) UV glasses and light, then 3)a halogen leak detector. If a leak is found, I have no choice but to recover the refrigerant and start over. This rarely happens if all the leaks are found by pressurizing the system with dry gas first. I am human (and a little blind), so I have on occasion missed one. The point is, don't just charge the system before finding and fixing ALL the leaks with pressure!....Rich

Phillytwotank · #13 06-30-2014, 10:13 PM

Quote:

Originally Posted by ROLLGUY

The only (well maybe not the only) problem with refrigerants other than R12 or R134a, is that no reputable shop will recover the refrigerant after testing if anything but R12 or R134a is found in the system. Yes you could bring it back after the system has been emptied (some have had the contents of their system "mysteriously" leak out), and they will work on it. Most shops do not want their refrigerant supply contaminated. I say most, as the reputable shops will hook up a gas analyzer before recovering any refrigerant to be sure of what they are recovering. They don't want to put R12 in their 134a tanks, and visa-versa....Rich

Understood. The ES is supposedly just that. Environmentally safe. To discharge into the atmosphere.

I guess it all depends on if mr subman is wanting to go down a DIY road or if he plans on having a shop do it all.

If he plans on having a shop do everything and the high cost of the original refrigerant is no problem, then I say definitely go with the r12.

If the r134 conversion was don't properly I think going back to r12 will be more complicated because the oil would have to be changed and the system flushed, new dryer and all of that.

ES I think would be the easiest option if he had a shop recover the r134 then just replace it with the ES. Same oil and dryer. Just put it in and go.

subman60 · #14 06-30-2014, 10:15 PM

Are the leak testing kits you can buy at places like Auto Z any good. It seems like the ones I've seen there have a UV dye and special glasses you use to find leaks. The company I worked for only sold to the residential and commercial shops so we didn't keep up with auto industry refrigeration systems. Most of our customers used leak detectors to find leaks.

ROLLGUY · #15 06-30-2014, 10:29 PM

Quote:

Originally Posted by Phillytwotank

Understood. The ES is supposedly just that. Environmentally safe. To discharge into the atmosphere.

I guess it all depends on if mr subman is wanting to go down a DIY road or if he plans on having a shop do it all.

If he plans on having a shop do everything and the high cost of the original refrigerant is no problem, then I say definitely go with the r12.

If the r134 conversion was don't properly I think going back to r12 will be more complicated because the oil would have to be changed and the system flushed, new dryer and all of that.

ES I think would be the easiest option if he had a shop recover the r134 then just replace it with the ES. Same oil and dryer. Just put it in and go.

All very true, I just wanted to make it clear that there are precautions that have to be taken. Most people don't know about the possible contaminating of refrigerants. From what I understand, ES12 is basically propane, so that is why it is allowed to be vented. I have no problem with that, but some folks might. I have plenty of R12 and 134a, so I won't be using ES12 anytime soon. I have been very happy with the systems I have installed and with the vent temps they provide. Most have been 134a, but a couple R12.