A/C recommendations for the MB vehicles - Page 9 - PeachParts Mercedes-Benz Forum

leathermang · #**121** 06-30-2011, 09:55 AM

John , I think you are talking about different fans....
I am referring to the one blowing air through the evaporator fins... and and that air needs to be in contact with the fins as long as possible to reflect the temperature the evaporator is actually getting to... low blower fan is the standard way the low temp of the evap is judged.
The condensor needs as high a fan speed as can be arranged or bought...

vstech · #**122** 06-30-2011, 10:10 AM

yeah, I'm not talking about service fans, I'm explaining to BC that the car won't produce low temp air driving the car at low speeds with 134. only on highway, or when the car is moving above 25mph or so...

remotemark · #**123** 06-30-2011, 11:12 AM

I'm sick of the crappy cooling I get from the 134 in my 84 W123 300D. In the shade or on a cool morning, I can get 55-60 degree air from the vents, but when it's hot here in Charm City, I'm lucky to get mid-70s, and when 95 and the muggies hit, it doesn't seem to do much of anything. So I've decided to bite the bullet and do a proper reverse conversion to R12.

I bought some 12 oz. cans of R12 off a fellow on CL ($100 for 16 cans). I've ordered a new R4 compressor, a new condenser (mine has plenty o' bent fins -- maybe 40-50% of them), a new receiver-dryer, and a new high-low switch. Does anything else need replacing to do this right? Any of the hoses?

I've found a good radiator and a/c shop and will ask them to do the following for me: 1. get out the 134. 2. hook up the hoses to their flushing rig and flush all of the oil out of the hoses and the evaporator as many times as they can. 3. install the new components. 4. pull a vacuum to see if there are any leaks. 5. charge with oil and R12 (I have to supply it for them).

Have I covered all my bases? What is the correct R12 charge for my car?

Thanks!

leathermang · #**124** 06-30-2011, 12:32 PM

First let me congratulate you on a super R12 bargain...
Second, you have left out the leak check by using pressure , R22 ( the by the book recommendation since it is EPA approved to vent the four oz used for the leak test into the atmosphere )and nitrogen or argon... pressure is the only logical way to test for leaks for several reasons probably already mentioned in this thread..
When you get the oil.... for R12 ... I suggest Castrol premium cold flow 500 ...
Are you going to put a new Txvalve in ? Might or might not be needed... and I do not know if R12 txvalves can be bought now... they may all be set for R134a...something to check on..
New orings installed with Nylog is recommended...
The new fittings to be proper for R12 .....and remover R134a decals on car...

remotemark · #**125** 06-30-2011, 01:42 PM

Thanks, I thought I got a good deal. I had bought some a year or so ago and sold it to someone who really needed it at the time for about twice that rate. I just got lucky this time. Most of it is in a case which has never been opened.

As for the pressure test with the R22, would that require an additional evacuation/flushing before charging with the R12?

leathermang · #**126** 06-30-2011, 01:52 PM

No, at the time you flush... you can vacuum it ... to get out an residual moisture... pressurize it with a dry inert gas.. nitrogen or argon, and the R22, sniff and watch pressures for leaks... then vacuum that out and charge with R12....or of course fix any leaks found...

wildest · #**127** 06-30-2011, 05:43 PM

Quote:

Originally Posted by leathermang

Yes, in place..
good thread by Dmorrision about that....
find a way to get to it.... good luck....
then spray cleaner and rinse repeatedly and make sure the drain out the bottom of the car is open and free during process and afterwards...
I recommend that thread so often I ought to put it in my sig... will when I find it again... Whunter found it lately and posted it...
Have you read all of THIS thread ? -----because that ref may be in this thread...

I have read all this thread, and I don’t think there was a reference to cleaning the fins on the evaporator in place earlier. I was mostly wondering if there is a preferred solvent to use.

leathermang · #**128** 06-30-2011, 05:59 PM

Photo step by step post showing a W123 evaporator removal (1983 240D and 1982 300TD)

I would think any solution of dishwashing detergent would be good... I think one of them is supposed to be better and cheaper than others dissolving grease... when used to soak..
that is the method of cleaning I think would apply..
but there may be things which smell like oranges or whatever that work just as good..

Ok..
" Dawn Direct Foam " rates best in both categories they tested..

vstech · #**129** 07-01-2011, 09:56 AM

Quote:

Originally Posted by leathermang

No, at the time you flush... you can vacuum it ... to get out an residual moisture... pressurize it with a dry inert gas.. nitrogen or argon, and the R22, sniff and watch pressures for leaks... then vacuum that out and charge with R12....or of course fix any leaks found...

I would not evacuate before checking for leaks.
if you have any, you will be bringing in more moisture, not removing any.
pressurizing with N2 or CO2, or Argon blowing that out, then pressurizing with the mix of R22 and N2 etc, will remove more moisture than a minimal evac will.
and you will not be introducing any moisture to the system!

vstech · #**130** 07-01-2011, 10:02 AM

Quote:

Originally Posted by wildest

Quote:

Originally Posted by leathermang

Yes, in place..
good thread by Dmorrision about that....
find a way to get to it.... good luck....
then spray cleaner and rinse repeatedly and make sure the drain out the bottom of the car is open and free during process and afterwards...
I recommend that thread so often I ought to put it in my sig... will when I find it again... Whunter found it lately and posted it...
Have you read all of THIS thread ? -----because that ref may be in this thread...

I have read all this thread, and I don’t think there was a reference to cleaning the fins on the evaporator in place earlier. I was mostly wondering if there is a preferred solvent to use.

the BEST solvent to use to properly clean the evaporator is professional evaporator cleaner. it'll foam and lift off the caked on cat hair/lint/etc from there and slough it down the drain. some types are made to foam and foam and not even need rinsing off.
that said, simple green in a 50% concentration does a pretty good job.
for the condenser, NOTHING does as good a job as true condenser cleaner. it has either an alkaline or Acid formula to attack the surface oxidation of aluminum and lift everything above that layer out of the coil.
it must be used carefully, and it must be rinsed off completely, but it will clean the coil the best. it should then be treated with a surface slicker with teflon for best longevity of the clean...

leathermang · #**131** 07-01-2011, 10:33 AM

Quote:

Originally Posted by vstech

the BEST solvent to use to properly clean the evaporator is professional evaporator cleaner. it'll foam and lift off the caked on cat hair/lint/etc from there and slough it down the drain. some types are made to foam and foam and not even need rinsing off.
that said, simple green in a 50% concentration does a pretty good job. for the condenser, NOTHING does as good a job as true condenser cleaner. it has either an alkaline or Acid formula to attack the surface oxidation of aluminum and lift everything above that layer out of the coil.
it must be used carefully, and it must be rinsed off completely, but it will clean the coil the best. it should then be treated with a surface slicker with teflon for best longevity of the clean...

As usual I totally agree...
BUT the last time I bought some of those professional cleaners.... one for the outside fins of home AC's and one for the inside fins ( less corrosive ) I had to buy a GALLON Each of the Concentrates.... and that was from that specialty AC place that shut down...
So if one can find it and afford it... go for it... those ' scrubbing bubbles' on the advertizements actually work when dealing with these pro liquids....

ROLLGUY · #**132** 07-01-2011, 08:51 PM

Just read all 9 pages of this thread, WOW! A lot of good info here. Someone asked about the R4 compressors here, and I don't remember seeing a reply. I have purchased several different brands of R4 compressors from different places. Kragen (now O'Riley) has the worst compressors IMO. The best one that I have heard is the Delphi (most expensive), or Behr. Most (if not all) of the R4's available are remanufactured, save maybe the Chineese knock-offs (stay away from these). Anyone else with different R4 experiences, please post.

leathermang · #**133** 07-02-2011, 10:28 AM

Rollguy,
If I was going to buy an R4 today .. I would call Tray Carlisle at Carlisle Auto Air in San Antonio...decades doing this stuff...
I have talked to him about them before.....and he is in the business day to day...and knows what brands are coming back in needing repair....that sort of up to date stuff...
He did convince me that some of the later serial number R4's were perfectly good to use with R134a due to having been ' beefed up' and that millions were in use and doing just fine... They do have some advantage in terms of size in some situations..
That is my suggestion... Call Tray...
Ok, another way of saying this is... the quality of the Branded Names can change over time... so someone in the day to day business knows the feedback from that potential... rather than just recommending a certain brand and someone buying that three years later when it is not even the same company....

remotemark · #**134** 07-05-2011, 04:55 PM

Kind of off-topic, but I ran into a guy with a Sprinter in the parking lot at the pool over the weekend. He had just finished his DIY a/c upgrade. He now has two compressors, three condensers, and three evaporators. The roof has two housings sticking off of it which look a bit like hood scoops. Each one has a condenser and just below it, an evaporator. Those two units run off of one compressor and the dash unit runs off of another.

It was like a meat locker in there. It's rigged up as a sort of half-work van and half camper with a full-sized bed in the back. I was tempted to ask to see the "if the van's a rockin' . . ." sticker, but decided discretion was the better part of valor.

Hit Man X · #**135** 07-05-2011, 10:37 PM

Anyone know (Greg

) if the fittings on the hoses in these cars are the standard 6/8/10/12 or if they are metric?