I thought I could survive without A/C in the new '83 300DT, as I had with my previous primary car, a '70 BMW 2002, but knowing that it's going to be hovering around the low tons until September (108F today), combined with a dark blue interior, and a total lack of shade in the middle of the day, I've committed to getting the A/C working. While I've been an amateur DIY mechanic for years, working on most everything barring opening the engine further than valve cover(s), this is my first Benz, my first diesel, my first post '76, and my first time working with A/C.

I was pleasantly surprised upon meeting the car to find that the climate control system controls (ahem) in the center console operate correctly, albiet without cold and without opening the center vents. I can hear the blower operating, and can feel air thru the side vents.

I called the premier local A/C garage, according to the phone book, who quoted me around $250 to test for leaks and $650 to fill the system with R12, which requires and includes the leak test. Is this as high as it sounds, or is it actually a typical price range for the job? And if it is typical pricing, is one getting screwed by paying it? Is the difficulty of the job that high? Should I just call around some more?

In any case, if at all possible I'd really like to do it myself. I've been nosing around Aircondition.Com, which is very general, and have re-read Diesel Giant's article multiple times, but I'm stuck as I haven't access to the equipment mentioned ("A/C recycle charge machine"). What can I do to diagnose the state of the system on my own? How do I test for leaks and test if the compressor is working properly? What tools do I need to do the job myself?

A simple step-by-step detailing the complete process of a total flush and recharge would be a total godsend. I'll take photos during my process and we'll have a definitive W123 guide!

Any help is much appreciated. Thanks!

The quoted $650 sounds high to me. I suppose it depends on your geographical location -- 108F sounds like Phoenix, maybe. You can do much A/C work yourself but the system has to be evacuated and recharged by someone with the appropriate license and equipment. For that you must pay, unfortunately.

Depending on how long the system has been low on Freon, and how much someone has tried to run the system, the compressor may have been damaged -- the lubrication oil for the compressor is part of the Freon recharge process.

If the ACC electronics work correctly, the compressor and Freon are the main things. The accumulator/dryer may need to be changed but it is not expensive, at least not compared to the compressor. If the compressor does need to be changed, you can do that yourself. The system must be evacuated first by a licensed individual. It may be that the system is already so empty that you can just open it up -- perhaps someone with more knowledge will jump in here.

In the meantime, shop around for a better price on the evacuation/leak test/recharge.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

You can do almost everything yourself If you are willing to do a LOT of studying ...
First go back to Aircondition.com and read the section on testing for leaks using Nitrogen and R-22...
After you flush you could call and just ask for that service to be done by a shop... or you could buy a small nitrogen cylinder.... if you are like me who looks for excuses to buy tools and equipment... ( I just got a five ft high one..but much smaller ones are available at welding supply places )
This is easily the best way to do that... and they tell why in a comprehensive way...
You can rent some of the big things you need only once and for short times.. like AC vacuum pump. If you have done all the other stuff carefully and correctly you will only need it one weekend... if not you will need it the next weekend also... but that is cheap and gives you a lot of power over the cost of your repair.
But it is nice that you got that estimate... so as you go along and find you can not rent some tools you can judge their cost against what having some shop do it ( and you not know how careful they were )....
Those other things you asked about .... like flushing... are well discussed in threads here on this forum... the search engine will bring them up...

I just overhauled my system. I bought a new compressor, r/d, exp valve, 8 cans of R-12, a new vacuum pump, flush gun and heated diode leak detector. And I did not spend that much. I already had a shop air compressor and a/c guages.

You guys've got me gung-ho on going it DIY; I want to learn everything and do it straight, a full overhaul (new dryer, compressor, expansion valve, etc.).

However, with these temperatures, it's sort of an emergency situation -- we'll have some solace late next week at 102F. I've been looking around, and it seems the best thing to do is replace at least the dryer and expansion valve, probably best the compressor too. If I put in an order on Monday for the parts, it'll take at least a week for them to get here; in the meantime I'll pick up some gauges and upgrade my air compressor, get certified, and procure some R12 -- using eBay, the full turnaround might be a week and a half. So now it's the middle of the week after next, and I've got all the parts. I'll rent the specialized equipment needed, and do a total overhaul and recharge (including a nitrogen leak test done at an A/C garage), which'll take another couple of days. All in all, I can estimate it'll take about two-and-a-half to three weeks to have my baby equipped with ice cold R12 A/C.

I'll have melted by then. I've been thinking: say I go out tomorrow and pick up some cans of 'SuperCool Extra Flush' and Freeze-12 (or R134? whichever's easier to use temporarily and then retcon to R12 -- I'm gathering Freeze-12) over the counter, and flush and fill according to the instructions provided. It seems like the best that could happen is that the A/C functions for two weeks before being overhauled and recharged correctly with R12, and the worst would be either finding out that the compressor is already broken or subsequently causing it to break due to the temporary conversion (I should replace it anyway, I'm thinking, and this'd make it a necessity).

Is my estimation correct, or are there any pitfalls I haven't yet realized which would make this quick-n'-dirty path prohibitive?

its 98 here and I wouldnt dream of fixing my ac, that why germans put the worlds biggest sunroof in these cars.

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1995 E420 Schwarz
1995 E300 Weiss
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#1991 300D Nearly Perfect
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#1995 E320 Touring
#1985 300D Sedan
OBK #42

"Is my estimation correct, or are there any pitfalls I haven't yet realized which would make this quick-n'-dirty path prohibitive?"

I do not think that plan will save you any time getting cool.
It will take you all that time to do the proper things to your system to put the R12 into it... if you stick the other in you will need to start over on many things including buying a new Rec/Dryer, all the orings and install them, flush again,... better to spend your spare time learning what the physical constraints are concerning the physics of AC and our particular Delco compressor ( no oil sump in it.. so oil miscibility is Critical for lubrication.
Start by reading all you can find at Aircondition.com knowledge base..
Start with the concept of leak testing with nitrogen and R22...
Then we can point out good threads on this site to read.

I also suggest right out of the shut you go to the epa site and get your open book test and license to buy R12... about $20 .. lots of theads about that here also...
and it spells out some of the best reasons not to use blends like Freeze 12... which is misnamed in order to mislead you .. it is 80 percent 134a...

It sounds high to me as well.Unfortunately many shops quote you a price,then slam you when they find lots of stuff wrong.I am not saying they are not a legit shop,its just the way business is done.I would sweat a little longer and do some research on this webpage,there are many knowledgable folks here that are more than willing to guide you through it,good luck Johnny

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85 300sd SOLD ,85 745i,95 740i,1972 Suburban,1938 International

Got my 609 this afternoon.

Only got to check a single place while in town this evening, Kragen Auto Parts, as everyone else was closed by the time I got in -- the heat's necessitating my becoming nocturnal. They hadn't any in stock, but the clerk said that they do carry one-pound frigen-baby cans of R12 -- best he could remember, last having sold one a couple of months ago: about $40! I'm going to check around more on Monday, but they did have Freeze-12 in stock at $8/lb, if I get stuck. This whole time I'd been under the impression that the Freeze-12 vs. R-12 debate was fueled by cooling efficiency and reliability/compatiblity alone; I knew there must be a cost difference, but had no idea it was so vast!

On Freeze-12 again, to clarify, I meant to flush the system as it is, without diassembling it (maybe I'll just change the o-rings at the evaporator valve..?) and use the existing evaporator valve and drier when temporarily filling with Freeze-12. With the Freeze-12 in, I'd do a thorough leak check with Big Blu and identify the culprit. Then, when everything's together at the end of the month, I'd flush again, repair all leaks, replace all o-rings, as well as both the evaporator valve and the drier, and the compressor itself, if I find that it's not working correctly with the trial Freeze-12, and fill with R-12 for good -- all if, of course, I confirm that Freeze-12 is too weak to continue with, which I'm quite sure will be the outcome. My hesitancy is concerning using the existing, possibly fairly ragged equipment with Freeze-12; for instance, could using the existing drier with Freeze-12 possibly foul an otherwise functional compressor?

My understanding is that Freeze-12 is a blend, concoted specifically to modify R-134a so that it may more easily be used in an R-12 system. An attempt to chemically simplify/aid the retrofit of R-12 systems by modifying R-134a to behave more like R-12.

I've still got to call around smaller A/C garages, too. Tomorrow's to be spent compiling and comparing costs and budgets: R-12, Freeze-12 and later R-12, with compressor and without, using local parts supply or mail-order, etc.

By the way, where's the best/cheapest place to get a new R4 compressor, beside eBay?

You are using bogus figures to compare on the prices.
Now that you have your license check out Ebay ..... or threads here where we have talked about ' scores' ...... the R-12 should be half what you were quoted.

According to all I have read your refrigerant change outs will require buying two new Rec/Dryers to hope to be safe. Which will negate much of what you think you will be saving not going with R-12 in the first place. Being safe to me means trying to make sure that you do not have moisture in your system long enough to create the acidic oil which will start to attack your system from the inside.

You can't flush your system without dissassembling it. Not in any reasonable definition of flush as used by air conditioning people.

"My hesitancy is concerning using the existing, possibly fairly ragged equipment with Freeze-12; for instance, could using the existing drier with Freeze-12 possibly foul an otherwise functional compressor?"--

Absolutely correct. You have done a lot of studying and almost have the overall picture.. hang in there and all of a sudden it will all fit together.
Normally you change out the Rec/Dryer each time the system if opened up. It only has a small but CRITICAL moisture absorbing capacity...and can't be cleaned or dried once contaminated... you don't even open it up until RIGHT at the time you are going to install it in your flushed cleaned system... then you immediately put the vacuum pump on the system so that existing moisture is taken out as best as possible... then it only has to deal with what can't be gotten out.... and should protect for years that way.

"My understanding is that Freeze-12 is a blend, concoted specifically to modify R-134a so that it may more easily be used in an R-12 system. An attempt to chemically simplify/aid the retrofit of R-12 systems by modifying R-134a to behave more like R-12."--

That is a description which comes from the people who are trying to sell you Freeze12 or other stuff...
When looking at the evidence concentrate on ' Oil miscibility" and" head pressures"... particularly since you are staying with your Delco...

Call Tray at Carlisle Auto Air in San Antonio to check for specials on new compressors ... and also run your plan by him... he may can explain the down sides better than I can... they have been doing automobile AC at the professional level for at least 20 years...

"$650 to fill the system with R12"

Make sure that you hold your hands way up in the air and look scared, because that's what you're supposed to do when someone robs you at gunpoint.

Shops now can buy R12 for very little more than what R134a costs them. Last year I bought it for $15 per pound, and although I have not checked this year, I strongly suspect it can be had for even less. At their rates they are charging you somewhere in the neighborhood of $150 per pound. FIND ANOTHER TECH. That one is a THIEF!

DO NOT use FREEZE 12 or any other junk refrigerant. I and many others have written numerous times on this forum about the reasons. Do a search, but don't contaminate your system with such trash.

Good luck,

Did some calling around: you're totally right. The average price was about $250 to fill, without checking for leaks, and I set a Wednesday appointment for a place that'll do it for $165.

In the meantime, however, I have got my 609. There's a local place that's got R-12 for $30/lb. (ahem), and NAPA will have a gauge manifold delivered next-day for $80; total about $170 plus tax, and I'll be able to recharge tomorrow and pin down the leak(s) with Big Blu -- plus, I'll be able to keep the gauges. Hmm...

What I forgot to ask about locally was oil. Is there a way to add it without removing the drier and compressor or using an injector? But that'd be pretty iffy, as I don't know how much lubricant might still be in there, right? I could fill and run it without checking, but the compressor might lock up with a total lack of oil. Would a lack of oil foul any components other than the compressor? Actually, I could probably pick up the o-rings at NAPA, remove and clean the existing compressor, drier and expansion valve, fill the compressor and drier with oil, and replace it all wearing new rubber. But, hell, that might ruin the whole price relation!

I know all this speculation comprises doubling some steps, but I'm about as desperate as I can be without wanting to ruin the entire system. I bought this sedan to use for summer roadtripping and am sort of freaking out as the days speed by -- it's probably heatstroke. Maybe I'll just succumb and let the garage do it.

"In the meantime, however, I have got my 609."--johnd

OK ! Now you are in charge of what happens and can do it right at the least cost.. Since you are getting guages why are you not going to install the R-12 yourself ( and buy it for the least you can on Ebay for instance ) ?

Oil is usually found either in regular quart containers ( and there is a tool to pull it out and install it with ) or in cans pressurized with the refrigerant you are going to be using ( so you use your can tapper just like the small freon cans).. with a couple of ounces of the refrigerant ...which you take into account when doing your weighing....

Only indirectly, but to a severe degree. Search for "black death."

"Would a lack of oil foul any components other than the compressor?" --johnd

No, the oil is strickly in there to service the moving parts of the compressor... in fact with some systems ... as with some dual evaporator vans and buses... they have a short cut of the oil... taking it out and putting it back into the compressor without making the whole trip around the system...