What did U pay 134A conversion - Page 2 - PeachParts Mercedes-Benz Forum

Renntag · #16 08-11-2010, 03:53 PM

Everything I have heard points to R12 only in the early cars shipped with R12.

I am keeping with this advice.

#17 08-11-2010, 04:01 PM

Quote:

Originally Posted by koya1893

As recommended from an A/C expert I deal with (one of few things) I don't do to my cars. Anyway, he mentioned the R134 operates at a much higher pressure and converting this particular year is not recommended. Instead he charge the system with Freeze 12, I think that's the proper ID for what's compatable with R12. 139.00 for a complete test and re-charge of the system.

Where would we be without the "experts?"

Beastie · #18 08-11-2010, 05:16 PM

Got it! , Jetmugg I know what you mean , I have his original invoice from EuroMotor Cars in Bethesda MD and the sticker was $40,624.00
That said I have not gone through his entire maintenance records yet since they are still at my Mom's house. However I am not certain that this was not converted already. I putzing around and went out and took a steel pin and removed the red cap close to the firewall and brake servo. It had some pressure and in fact also had what appeared to be a bright yellow fluid in with whatever refrigerant is in there. I am guessing a leak detector ? similar to one used on my Dodge Durango a few years back. Question is there any color difference in leak detector/sealant from 134 v.s. R12 ? Also I expected to see a regular schrader valve. Instead the connector here as well as the one next to the aux fan were both of a quick disconnect type. There are no stickers anywhere under the hood indicating a conversion however I know Dad had almost all of the a/c system replaced at some point in the last 10+/- years.
The hose coming from the firewall does have a colored band around it though
and it is also a bright yellow. It has a printed on it but kinda hard to see it right now. Thoughts ? I know a shop can test and see but I was wondering if any of what I have rambled on about might be indicative of the refrigerant.
Thanks
Alan

vstech · #19 08-11-2010, 06:49 PM

with no stickers, it's hard to know what's in the car.
obviously something other than original is in the car. it could be FR12 or 134... you'll be better off getting it analized before continuing.

my123ca · #20 08-11-2010, 07:29 PM

If it has quick-disconnects, it most likely is R134A.

Beastie · #21 08-11-2010, 08:31 PM

Yeah, I agree it is probably 134 ( not sure to be happy about that or not)
I will have to find a shop that will do JUST the check.
Thanks
Alan

Beastie · #22 08-12-2010, 12:55 PM

Got it checked and it is 134A. Happy Sad ? anyway last night when the outside temps cooled to a comfy 92 degrees I went out and did some other troubleshooting and here is where I am.
1. Checked for power to Low pressure switch good
2. Put in some 134A from a stash I have and it took very little to get the compressor to kick on. After I let the car idle for about 5 minutes I drove about 1 mile and let the operating temp come up. The air coming out was only slightly cooler than ambient temp. I have an infrared temp gun as well as a the rectal probe. I am running over to a friends home to retrieve my 134A Manifold gauges
and check the pressure on high and low side. Here is the thing the Aux fan never cut on. My question is this should it be on the whole time the A/C is running and the compressor engaged ? I am going back outside to troubleshoot
if power is going to the fan or and and if not where does it stop. I am certain there is a relay, is it in the engine bay fuse box ? As I stated before this car sat for a quite a few years and was driven infrequently ( by my younger brother who ran it out of fuel a few times and could not for the life of him operate the primer pump)
3. The local shop where I had the refrigerant diag. said they had a few tricks to get these to cool better even with the 134A in it. Any one have ideas what he is talking about other than a "Magic" and potentialy lethal additive. Or possibly a larger condenser ?
Thanks
Alan

thayer · #23 08-12-2010, 01:39 PM

According to VSTech (and I will typically agree with him by default) you have a fine condensor. The Aux fan comes on when the temp relay senses the condensor needs it. You can always jump the blade connectors and have it run all the time. The aux fan has it's own fuse in my 83. Mine cycles as needed. I installed a second aux fan which helped visibly on the high side pressure. Off I was above 200 and on I was below 200. It was fun watching the gauge move by blowing air over the condensor.

other ideas for getting it to cool better.
1. Look for dmorrison's thread on cleaning the evaporator. Drop the blower and stick a small shop vac in there. Pull out all the leaves and acorns ect.
2. tint the windows

Beastie · #24 08-12-2010, 01:52 PM

Thanks, However what about your low side pressure ? If I got you right you have 200 psi with the engine off on the high side. I may just not have enough
134A in the system ( you were talking 134A right ?) The compressor now comes on as I said and I did check and I do have a fuse just for the aux fan. It is of the better copper tips and I cleaned it anyway. I will check the temp switch after I jump the fan. If you have a minute please confirm your pressures if you have the 134A.
Thanks
Alan

Jetmugg · #25 08-12-2010, 02:16 PM

On my W201, the aux fan doesn't run the entire time that the compressor is running (although it might cool a bit better if it did). I believe that the secondary electric is triggered by a pressure sensor on the high-side of the compressor.

I believe that having the aux fan run whenever the compressor is engaged would be of some benefit.

Since it's already a 134 system, perhaps you might want to evacuate the entire system, then "weigh in" an appropriate charge of 134. There is a rule of thumb about how much to add to a 134 converted system, but I'm not too sure what it is (something like 20% more than the original R12 capacity).

SteveM.

thayer · #26 08-12-2010, 02:25 PM

Quote:

Originally Posted by Beastie

Thanks, However what about your low side pressure ? If I got you right you have 200 psi with the engine off on the high side. I may just not have enough
134A in the system ( you were talking 134A right ?) The compressor now comes on as I said and I did check and I do have a fuse just for the aux fan. It is of the better copper tips and I cleaned it anyway. I will check the temp switch after I jump the fan. If you have a minute please confirm your pressures if you have the 134A.
Thanks
Alan

Sorry, I wrote too fast and was unclear.

With the engine and the ac running on max with windows down I looked at my gauges. High was around 200 and low was about 25 30ish.

without my aux fan I was above 200 and with my fans running the high side pressure would drop to below 200, around a 5 to 10 lb drop.

All that to say, the aux fans are awesome. If you run them all the time by jumping the spade connectors, I will smile and know the good you are doing.

thayer · #27 08-12-2010, 02:27 PM

Quote:

Originally Posted by Jetmugg

On my W201, the aux fan doesn't run the entire time that the compressor is running (although it might cool a bit better if it did). I believe that the secondary electric is triggered by a pressure sensor on the high-side of the compressor.

I believe that having the aux fan run whenever the compressor is engaged would be of some benefit.

Since it's already a 134 system, perhaps you might want to evacuate the entire system, then "weigh in" an appropriate charge of 134. There is a rule of thumb about how much to add to a 134 converted system, but I'm not too sure what it is (something like 20% more than the original R12 capacity).

SteveM.

20% LESS!!!! than the original. 134 compresses at a higher pressure than 12 so it takes less to fill the system.

put 2lbs in there and see if you get close to 40 degrees. if you do, I'd leave it alone. there are some discrepancies as to how much 12 was supposed to go in. I put 2lbs 134 in mine and am getting 40.

holtonmusicman · #28 08-12-2010, 03:58 PM

I purchased a Compressor and Drier through Advance Auto for less than $200. Installed them and replaced all the o-rings myself.

Had my local shop evacuate and charge with R134a and my AC is so cold (even with 104 degree temps and 115-120 heat index) I have to turn it down while I driving it around town.

R134A is $8 a pound here . . . R12 is $75-$80 per pound . . . it was worth is to me to convert as my old AC compressor and drier were off the vehicle and I had to replace them to get AC to work anyway.

More shops do R134A here than R12 as well.

Just my two cents . . . but the R134A works very well for me.

Beastie · #29 08-12-2010, 04:17 PM

Holtonmusicman, I am glad to hear that. As others here have said the original system was not designed for it and so should not work as well as the R12. Again as I have said the 134A works well in systems designed for it. Hell I can put a steel water bottle in the cup holder next to the front seat in my suburban
aim the air vent at it and it will cool down quickly from room temp in the house
get in the car and drive 20-30 mins and it is cool enough. Anyway I have tinted windows on my 500E ( I bought it from Arizona and it came that way) and I will add that to the 300Sd as well as a rear blind as soon as I decide which one.
On a side note my beloved but gone 89 Range Rover ( 140K + miles) had a GM
A/C system that would get cold but like the one in my Porsche it just did not blow too darn hard ( okay go ahead and snicker now). The fix for that came by way of the Marine trade. A buddy suggested an inline/thermos fan be brought in to play. I bought it for about 30 bucks and installed it slightly under the dash so it could not be seen and damn that thing would put out some airflow. I used to wash my RR after a romp through the mud and then let it idle with the fans on high while I soaped up the exterior and the damn airbubbles that were blown through the air gaps at the rubber seals were huge. Sorry to ramble since it is raining still my wife brought me a cocktail to the study and I am on my third. No test driving tonight and no power equipment use.
Alan