1982 300CD W123, much improved air conditioning!! Klima parallel flow condenser
 

I had one of these parallel flow condensers from Klima installed. Greatly improved Air conditioning! Prior to this, the AC wouldn't work well in stop and go driving on a hot day. Now, it works well in all hot conditions. Don't forget about the new expansion valve.

https://klimakit.com/product/parallel-flow-condenser-upgrade-kit-w123-2/

https://klimakit.com/product/thermal-expansion-valve/

Hey, that's awesome! Great news. Nothing like a properly functioning ac system....on a car, or anything else. Truly, one of man's great inventions!
What about your compressor? Original, or had you already replaced that previously? Filter/dryer? It gets a little pricey, but the end result is well worth it in my book.
Air conditioning used to be considered a luxury. In my opinion, it still is. And, luxuries cost money. It's just more commonplace, these days, and "built in" to the cost of new cars. Considering the cost of new and used vehicles now, it's a luxury alright. Cheers!

My existing A/C compressor was working well. For me A/C is a necessity since I use my 300CDs as daily drivers.

Klima offers good kitted solutions, though pricey. I have bought parallel-flow aluminum condensers for my 1960's Mopars for $50. Klima's gives you the proper M-B fittings and attachment brackets, but for $260. If re-hosing, might be preferable to change to more standard O-ring tube fittings, which I recall are #8 on the inlet and #6 on the outlet (liquid line) and use a cheaper, commoner condenser.

Re compressors, I had a Sanden on my 1984 300D for around a year, until Rollguy's custom bracket cracked, so went back to an R-4. Both cool about the same, which is "not good" when sitting at a long stop light. But, our 2002 Chrysler 3.8L is similar and it has 2 more powerful electric fans (no mechanical fan). Once moving about 30 mph, both vehicles blow cold air.

Exact same here. Did the Sanden. Vent temps didn't drop until the PF condenser was installed. If you have a working R4 system I'd leave the compressor alone and just change the condenser. If you're willing to bend the brackets on the stock condenser it can come out through the front. I did the whole thing with the radiator just tilted back with the top 2 clips removed. Their PF condenser saves a lot of R&D/prefab work on removable brackets, matching the stock mounting points, and plumbing the hard lines into the engine bay. I did add Loctite to each bracket screw.

I was wondering when the AC threads would start showing up this summer:D

my last w123 ( red 4 door ) had ice cold AC with stock r4 and condensor weird as i'm in australia :/

I just hope when i get my latest w123's AC sorted it's just as good.

do the later w123's have a different condensor ? the ( red 4 door ) was a 1982 and my new w123 is a white coupe from 1985 if that makes a difference

Math, I'm pretty sure they all had the same condenser.

Y'all use hydrocarbon refrigerants down under do you not?

I use HC refrigerant (Duracool) in 6 of my 7 vehicles. It works slightly better than R-12 and much better than R-134A. I understand it has long been popular in Canada, where my bottles have shipped from. I did hear of an Aussie story where an AC tech there purposely staged a fire with HC refrigerant to "prove" how dangerous it is. It isn't, indeed that is the only fire I've heard reported in millions of cars using it.

A few years ago I tried an experiment. I added a second auxiliary fan to the condenser. I thought this might help. I can't say that I noticed a difference. It was a nice try though.

http://www.peachparts.com/shopforum/...17-aux-fan.jpg

It would only help if you going less then 15mph
cleaning those fins would help more.

There also used to be a video circulating of a Porsche 924/928 club one of whose members had an overly long refrigerant hose severed by a fan blade which then came to function as an underhood flame thrower.

I find that the hydrocarbon works well at speed, not that well when idling. It certainly beats 134 which in addition to not cooling well also destroys compressors on the regular.

R134a Operating Pressure
 

Greg ;

What is the low side pressure you're using ? .

My '82 240D has one of Rich's SANDEN / PF condenser mods, it used to blow ice cold, then after a year or so tapered off to maybe 70* F at the dash center vent .

I stopped doing AC repairs when this was a new car so I'm a bit rusty .

Yesterday I bought one of those $35 18Oz recharge cans with a low side gauge on it and discovered my system only had 15# in it, I slowly added R134a with the windows open and the AC blower on high, when I reached 34# I stopped and buttoned it up, took a test drive :

At freeway speeds I now get 58* F at the dash, when I stop for a traffic light it creeps back up to 73* F, drops back down as soon as the car exceeds 25 MPH .

I know R134a used lower pressures than does R12 but I don't know what's too much .

What you're running would be helpful .

TIA,

Hi Nate,

On my blue 300d I noticed my vent temps were creeping up. It just didn’t seem as cold as before. I was getting 35 F drop below ambient (45 at vent on 80 day) but now I was seeing 53F at the vent on an 80 F day…in other words a 27 F drop.

I’ve been tinkering around with it and I have come to the conclusion that I may have a combination of too much refrigerant and too much oil in the system. I put in two cans of refrigerant and 8 oz of oil.

I rebuilt the system with new hoses, pdf condenser, 134a and a R4 rebuilt two years ago. The cooling was sufficiently good but never ice cold. And it seemed to get worse this summer. I recall it being better.

My wild guess is that I put in too much oil and I’m choking up the bottom circuits of my of my of condenser. I intend to drain the entire system and start over again at some point. The car has sat a lot during the pandemic…does the oil accumulate down there if you let it sit? Anyhow, I’m finally admitting I don’t know Jack about AC and I will probably have it professionally evacuated, flushed, oiled and charged.

Probably a wise decision. AC is unlike any other system in the car. Proper charge and oil amount are absolutely critical. As is knowing low and high side pressures and temps during operation. Also, ambient temps are important when this work is being done. Can you "shotgun" it and have good results? Sure, it's called luck.
You've obviously spent some money on it. With the rebuilt compressor and PF condenser (new filter/dryer, too I hope), should be nice and cold. I'd leave it to the pros...

Oil & Operating Pressures
 

Thanx, I'm hoping some one will post the low side pressure of their system when it's working properly .

Yes, too much oil will indeed raise the vent temps but first I'd look at the operating pressure as too high with R134a will quickly reduce the systems ability to shed heat, causing warmer dash vents .

I've talked to quite a few AC shops and none will watch the pressures, they want to either go by weight (there's a scale that holds the can, as the can empties you can see the weight go down) and others (most it seems) will use a fancy machine that you put in the vehicle info or the amount of charge from the sticker on the core support and press 'GO' and it does it automatically from a large Freon tank .

This isn't any good because our W123 cars were specc'd out for R12 and you need less volume and weight and pressure when using R134a so it's not quite "shotgunning" it .

I don't want to add too much .

This morning before sunup it was 69* F outside, at freeway speed I was getting 48* F at the dash vents, I'm sure it'll do better than that .

Don't be in too much of a rush to flush the system, yes flushing is a very good thing but you need to flush the evaporator too or there's no point .

I'd avoid any "ac shop" that didnt pay attention to the pressures. Pressure tells you the temp of the refrigerant. The lower the pressure the lower the temp. Pressure and temperature are directly proportional in an ac system. If low side pressures are too low you run the risk of freezing the evaporator. There is no 1 correct pressure. Varies from system to system. If you're "shotgunning", gotta know "ballparks"....

Sorry Nate, I don't know my pressures. I don't have a gauge

Since this looks like a general A/C thread - I've been looking into W123 parallel flow condensers and see that some people have installed dual condensers. There's a 14"x23"x44mm double-thickness parallel flow condenser on AliExpress that looks appealing to me. I could have a local A/C shop make hardlines for it to connect to the stock W123 hoses. If I've measured it right, there would be roughly 1/2" between the condenser and radiator.

I added a W126 aux. fan plus manual override switch to my '80 240d to help stop-and-go A/C performance, which is somewhat passable (about 35 degree drop) but I want better. It might also be possible to install a higher volume interior fan from a different car too.

Here's a fairly short overview/article of what's goin on with the ac in your car. It gets pretty "deep", but try and hang in there and get a general understanding. The previously posted "chart" is good if you want to know what pressures R134 is at various ambient temps. Unfortunately, ambient temp isn't really what you need to know. Kindly observe the charts at the bottom of the page. What they show is the temperature of the REFRIGERANT for a given PRESSURE. So, you need to know the pressure in your system (both high and low sides) aka "suction and discharge", in order to determine what's goin on with the refrigerant. Using the first chart, find 32 degrees F. You'll see the R134 pressure is around 28 psi. In other words, that would be your evaporator or low side pressure/temp and it's right around freezing (too cold). Let's say you want to keep your evaporator from freezing (good idea), so at 35 degrees F. the pressure should be around 30 psi. These pressures are read at the gauges that are connected to the high and low pressure sides of the ac in the car.
Keep in mind this an EXTREMELY simplistic example, I have just given, and not meant, BY ANY MEANS, to be used as any kind of instruction or direction.
Also keep in mind, before charging a system (if it's completely flat-no pressure) it must be evacuated first. Drawn into a vacuum. All traces of air must be removed. AC is a complicated, skilled trade. Yes, "anyone" can mess around with it and maybe have a bit of success. You can also waste a lot of money unnecessarily, possibly ruin a new compressor. And finally, it's a bit dangerous. Eye protection and gloves are a must. Freon under pressure can cause serious burns (freeze burns) and systems under pressure can burst throwing parts all over.
I'm no expert and not trying to discourage anyone. Just be careful. I've had the good fortune of a very good friend who's an expert in the field and has had me "under his wing" for a few decades. I wouldn't know anything if not for him (and I don't know much).
Not sure who gets credit for this phrase (one of my favorites), but it definitely applies here: "A little knowledge can be a dangerous thing".
Stay frosty, my friends. And, be cautious. Please!

Pressure-Temperation Relation, Superheat and Sub-cooling - NETHMAL PERERA (EIT) BSc Mechanical Engineering

Not much. I did all the work myself. A few hundred in parts. I did the same to my 65 f100 which had amazing results. Much bigger of condenser on that truck and a Sanden 5. The pf condenser was a cheapie on eBay. I made the hoses out of Galaxy and Futura barrier hose with fittings I bought on eBay. I used two driers because I had to crack the system twice 1st when I discovered one of the old hoses had a slow leak, then second when I added the of condenser. Each time I added a little PAG oil to make up for what I thought spilled out on the floor. I may have put in too much.

Wow, I'm impressed. Way to keep costs down. Dryer is about the cheapest part of the whole system, so no biggie. Would love to see some pics! Or, maybe a parts list and sources. You did a great job! Cheers!

123- I have a photo rich thread here. Posts 100 and up show the AC work which was done off and on for a year. I mention most of the places I got the stuff. Basically eBay motors sellers who specialize in custom AC parts. It was surprisingly inexpensive. THe 300D cost me about $500 in parts because it included new pods and electronics and the truck was $300 because it was a more primitive system.

The one thing I didn’t mention is the u bend em tubes from vintage air that I used on my pickup. Available from Summit. I didn’t use them on the 300d but they would have come in very handy for fitting the pf condenser in the tight quarters.

http://www.peachparts.com/shopforum/diesel-discussion/394730-got-1985-300d-turbo-7.html

U bend em. I had no idea how to flare AC o ring fittings so I bought these to do the hard lines in my pickup. On the pickup I ripped out it’s old under dash York based system and cobbled together a condenser, evap, Sanden 5 and hoses. If I turn the mechanical bulb thermostat down too low I can see ice forming on the evaporator. All with 134a. It must be the giant of condenser I fit on the truck. The evaporator was a Mustang replacement IIRC.

https://live.staticflickr.com/65535/...33a6e1e366.jpg

https://www.summitracing.com/search/product-line/vintage-air-u-bend-em-refrigerant-lines

I learned most of what I did off the guys here. Basically I bought a bunch of parts and bolted them together. My system is solid and doesn’t leak. The subtleties of refilling 134a and oiling a pf condenser are still vague.

THANK YOU for the links and pressure chart ! .