converting 134A - PeachParts Mercedes-Benz Forum

Beastie · #1 05-19-2011, 11:09 AM

Okay, I have read all the threads about pros v.s. cons on changing over. I have a question though. On a fully operational factory a/c ( R12) what is done when converting to 134 ? Is it just the pressure fittings for the high side and low side with the schraeder valves in them ? If everything is currently working should it be simple or do all the "O" rings have to be replaced at connections ?
Thanks
Alan

vstech · #2 05-19-2011, 11:14 AM

if everything is working there's NO reason to change to 134...

but if you really want 134, a PROPER conversion involves changing the pressure switch, removing the mineral oil, including changing the reciever and flushing the lines and coils internally., and installing ester oil or PAG, if you change the compressor too. and REALLY REALLY well cleaning the condenser (actually, this is just standard maintenance, not anything to do with the changeover) then the fittings get changed, and a proper label gets affixed to the radiator support.
but again...
if the system is working properly now on 12, there is no reason to change to 134!!!

oh, and the soft lines should be replaced with barrier hoses if you change to 134 too... which, yes means all new o-rings.

leathermang · #3 05-19-2011, 11:14 AM

You have a fully functioning R12 system at this time and have read all the threads....and are considering changing to R134a ?
Please explain why.
Perhaps you have missed some of the most important points in those threads.....

Edit : Vstech posted while I was trying to figure out how hard to come down on this concept.... LOL

vstech · #4 05-19-2011, 11:16 AM

Quote:

Originally Posted by leathermang

You have a fully functioning R12 system at this time and have read all the threads....and are considering changing to R134a ?
Please explain why.
Perhaps you have missed some of the most important points in those threads.....

Edit : Vstech posted while I was trying to figure out how hard to come down on this concept.... LOL

ha ha. I type faster than you!~

leathermang · #5 05-19-2011, 11:18 AM

Quote:

Originally Posted by vstech

ha ha. I type faster than you!~

No, I had to work to (even ) be civil in my response.....LOL
Mulling and calming time do not count against typing skills....

#6 05-19-2011, 11:20 AM

I agree, I tried 134a in my 300D at one point, then had it converted back to R-12. There is no good reason to convert it.

vstech · #7 05-19-2011, 11:21 AM

Quote:

Originally Posted by leathermang

No, I had to work to (even ) be civil in my response.....LOL
Mulling and calming time do not count against typing skills....

yeah, my mod duties have gotten me better at civil responses and it's almost second nature at this point...
still, I think I covered both sides of his question.

Beastie · #8 05-19-2011, 11:42 AM

I was luckily prepared for this onslaught ( although thanks for tempering and editing you replies) The system was operational last summer now it is not. I started looking things over and found some evidence of oil around the low pressure/fill port. I removed the cap and found the spring,plunger/core of the valve unscrewed to the point that the refrigerant had leaked out.
At this point in time I do not know if this was ever converted to 134. There is no sticker indicating such. To refresh- I got this car from my dad who is the original buyer brand new from dealer. He has an extensive file of every bit of maintenance ever done to it. However it sat off and on for 5-7 years and was driven infrequently during that time. Also my mother and younger brother had some repairs done but unlike my Dad ( now with dementia and a touch of Alzheimers ) did not file away or keep the receipts. It is possible it has already been converted and from what I can gather the way to tell at this point is whether or not it has the 134 fill valves or not. I agree about r12 even for the higher cost. When I had the a/c redone in my 68 caddy I kept it r12 and replaced everything plus a larger radiator ( I could get frost at the center vents on a humid day) I have done major a/c repairs on my own before but that's about 20 years ago. Whats is the best way to see which valve type is installed

vstech · #9 05-19-2011, 11:52 AM

color coded caps.
if it has a red and a blue cap, it's been converted.
also, R12 has outside threads on them, 134 has a single line on the outside of the fitting, like a large air hose connection.

Beastie · #10 05-19-2011, 12:19 PM

VS tech, Thanks, that is the info I am looking for. I believe it has been converted but need to go to the garage to double check.
On the one hand having the 134 recharged without any other mods will be cheaper ( as for many, money is very tight at the moment) although yes it would be nice to have the cooling power of the r12.
Thanks I will update shortly.
Alan

Beastie · #11 05-19-2011, 12:31 PM

Yeah ( short lived until it Washington DC northern VA heat and humidity ) it is 134 which just means I need to get the a/c recharged, windows tinted and park in the shade. I have a question though. One shop I spoke with previously said they have certain "tricks " they do to make the 134 work much better.
I do not want to start the old threads up about propane and other mystery gases. I do want to know about minor mods for top efficiency from this unit besides proper oil, charge and clean fins on the condenser. I will be using this for my daily driver most of this summer and was curious if a different pulley size to over drive the compressor and or changing the temp that the elect fan kicks on. I have not looked this system over completely but do know I will be changing out the receiver dryer before recharging it. Thoughts

sjh · #12 05-19-2011, 12:32 PM

I know one tenth of what the senior technical know on this matter and have less then 1% of their experience. But I will tell you what happened to when I graduated from college.

I could not afford the cost of repairing my R12 system. I had just graduated, terrible job market, etc.

This is what I did. It was not morally appropriate but I'm sharing it because of the technical consequences.

I bought the $15 kit, vented my R12 to atmosphere, did nothing else to prepare the system and filled it with one can of 134a oil and 2 or 3 cans of 134a.

For the next 15 years I would add between one to two cans a year as the system leaked. When the car was sold no money had been spent for 15 years to repair/improve the AC, it still worked well, including a year in Dallas and gave no indication that it would not continue to do so.

I neither attempt to justify my intentional polluting of the atmosphere nor in ANY way suggest that anyone do this.

I am saying this extremely crude conversion worked for 15 years.

I would not repeat my actions today. Some of us are slower at becoming adults then others.

Beastie · #13 05-19-2011, 01:11 PM

I agree. Now on another question. Are the schraeder valve insert different and a/c specific? I have a sealed container of new ones.
Alan

leathermang · #14 05-19-2011, 01:12 PM

Quote:

Originally Posted by Beastie

I was luckily prepared for this onslaught ( although thanks for tempering and editing you replies) The system was operational last summer now it is not.

WHAT BS !!!!

You start out in first post with ' Fully Functioning System " question ....
then say it is not operational.....

sjh · #15 05-19-2011, 01:17 PM

Quote:

Originally Posted by Beastie

I agree. Now on another question. Are the schraeder valve insert different and a/c specific? I have a sealed container of new ones.
Alan

It's been quite a while. As best I recall the kit was just two aluminum fittings, possible with some type of shrader within that screwed on top of the existing fittings. I do not remember removing the existing fittings. It's been quite a while.

Just to be clear I do not recommend the venting (obviously) nor using this simple approach. vstech, leathermang, etc KNOW what they are talking about in these areas. I do not.

I'm just sharing what occurred one time. The odds of that working again may be 1:2 or 1:100. I cannot say.