Main.TrailIndexPage | Cooling and Air conditioning | Air conditioner


This component is part of Cooling and Airconditioning.


Mercedes-Benz Air Conditioners were a dealer installed item. This was to ensure that the owner would have an air conditioner with good availability of spare parts in the local area and to be have technicians familar with the limited number of authorized AC brands used in these cars.

As with other dealer installed items, AC units often do not appear on Data Cards. AC's were a more popular option in the USA than in Europe and became more numerous in the later cars.

Probably the AC brand found most often in US W113's is Frigiking. Other brands included Kuhlmeister, Behr, and Thermoking.


Describe, in general terms the function of this component. Meaning what is it there for and what role it plays. Describe how it works, the inside mechanism. Use diagrams to explain.


Describe common maintenance procedures, and common faults that may occur. Describe how these may be diagnosed and resolved. Again, include diagrams, photographs and explanations. Where possible, include measures, tolerances, weights etc.

  • Symptoms when it faults
  • How to test if it is faulty - what tools to use
  • How to fix / change

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General Comment on Air Conditioners

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Will says: the only way I know to get oil out of the A/C compessor is to turn it upside down and let it drain out. This won't work if the condenser is still in the car. Use compressed air for that. A/C shops have machines that are designed to flush the system. Always replace the receiver/drier. It is the filter for both dirt and water.

My '66 Euro 230SL has no air conditioning, and I'm beginning to wonder if I should add it. For instance, there is currently a Kuhlmeister under-dash unit for sale on ebay that I could bid on. My questions are: Do these units work? How dificult are they to add to the car? If I were to buy this under-dash unit, how hard would it be to find the rest of the necessary parts? Is there somewhere else I should go to find an under-dash unit, etc? What other words of wisdom or experience can the group offer?

I would strongly recommend you convert it to a rotary compressor such as the Sanden. I'm using the model 505, it's small and it does a good job, especially with the hard-top on. The old piston compressors cause a lot of vibration and you usually have to raise the idle speed in the summer to prevent stalling. With the Sanden, I can barely tell it's engaged, and I don't need to raise the idle in the summer.

I am looking for an ac system for my 66 230sl. I have had a few replies to my search and I am very grateful. The problem is I am not sure what system is correct for my year. Or if there is a correct one or it just depended on what dealer installed it. If you know the answers to my questions please help..

Tom Hanson: MB used Frigiking, Kuhlmeister, Thermoking, and Behr over the years. I don't recall what went into a 230SL, but it was one of the above. I lost my a/c manuals on that car.

It's been extraordinarily hot in Washington D.C. and I notice that my A/C blower is not particularly strong. I am wondering if this is characteristic of the system or specific to my unit-maybe I am having RPM problems with my fan. Also, I am missing one of the circular vents at the bottom of the blower unit. Anyone have a source for old Frigiking parts?

I have the same AC in my 1969 and I recently rebuilt it. The blower should have three speeds; low, medium and high. When set to high, it should blow very hard, but most of the air will come out of the vent on the far right since it is in a direct line with the blower. There's not much you can do to get the air to flow evenly from all vents, except to move the louvers around a bit.

My unit, which was converted to R134a, will keep me comfortable (but not cold) with the soft top even in South Texas summers. With the hard top, it will get cold. If your blower does not have three distinct speeds or if the air flow from the far right vent is weak, perhaps there is something wrong with the fan moter or there is something blocking the air flow.

When I rebuilt mine, I found dirt, leaves and other junk in there (thanks to the previous owner). I have a wiring diagram for the AC that I can email to you if you need it. Other Frigiking owners, please offer your experiences as well.

Question: What exactly did you do for the conversion to 134. Did you change out the condensor? I've been told the higher pressure of the 134 warrants a look at a condensor that'll handle the higher pressure.

I changed the dryer and all of the fittings. The hoses were changed as well. The condenser was not changed and was more than able to handle the pressure, but I had it recored anyway, since it was so old. So too with the evaporator. The oil in the pump was changed to a different type that is compatible with R134.

The pump worked perfectly for about a year, but eventually had to be replaced due to unrelaiable leaking seals. If your pump is old, I'd have it replaced; they're not very expensive but a real bear to change. The entire job cost about $ 650 at a local AC shop, but I removed the unit myself to save a few bucks on labor.

While the condenser was being repaired, I disassembled the entire unit, repainted it, repaired things here and there and rewired it. I put in a LED in place of the incandescent lamp so I would never have to change it. I also cleaned and lubricated the blower motor and balanced the two squirrel cages. Of course, you can continue to use freon; it's readily available, cools a bit better than R134 but is more expensive (and less environmentally friendly) than R134.

Question: I'd like to put back my AC condenser, hoses, evaporator, etc. into the car, but they have been sitting around for a while. Although I did cover the openings, there may still be some dust or something that go in, also I'm not sure whether I'm going with r12 or r134a, so I'd like to flush whatever lubricant is still in there too. Is this necessary at all or should the whole system be flushed once it's all back together?

Your worst enemy to an AC system is moisture. The ends of disconnected AC components should always be capped. You can flush the hoses with one of th flush kits available for this purpose, to remove residule oil and any "dust", however the filter/dryer will take care of any minor desidue. The moisture will be expelled when you draw a vaccum on the system before charging.

Let it run for a while after achieving the vaccum. The moisture needs to "boil off and be expelled. Although I don't agree with the reasons for removing R12, I'd go ahead and switch to R34A. It may not be quite as good, but in most cases, you'll never knotice the difference. Also it's available, and "LEGAL". Go for the Synthetic Oil, it'll accept a small amount of the oil mineral based oil. The PAG oils won't.

I would stick to R-12 if I were you. I have read a few posts that describe the 113 A/C as marginal and R-12 is about 15 percent more efficient that R134a. Having converted My Saab to 134a and then converting it back to R-12 I can state that 15 percent does make a difference, luckily I have 30# of R-12 left over from the good old days.

I think that flushing is a good idea but more from the standpoint of getting rid of all the old mineral oil in the system rather than making sure every last speck of dust is removed. Mineral oil is not compatible with 134a and even if you charge it with R-12 now it would be nice to be able to "drop in" 134a at a later date so it is a good idea to get rid of it when it is convienient.

I would also use Ester oil since it is compatible with 134a and any old mineral oil in the system that may be left after flushing. Please make sure that if you charge with R-12 that it is compatible with the Ester oil, It has been awhile since I did my Saab and I can't remember if it is.

There's an old line outfit here in the Tampa Bay area that deals in old auto A/C systems. They rebuilt the old Fridgidare compressor for my 280SE 4.5 last summer, did it well, reasonably priced & in a timely manner. They were recommended to me by an ex Cadillac dealer who has used them for years for his old Caddys. They also give phone advice. They have a catalog too: Classic Auto Air, 2020 W. Kennedy Blvd. Tampa, FL 33606.

Ester OIl (a synthetic) is my choice for R34a. I much prefer it over PAG oil. If you decide to keep R12, I think you'll have to use the mineral oil for R12. R34a uses Ester or PAG. I built my own system using a Sanden rotary compressor and oversized my condensor, in front of the radiator, and have been happy with the cooling. It's not nearly as good as my wife's Chrysler Van, but then it's still an under dash unit. If I ever have to remove my heater assembly, I'm going to see if it's possible to install the evaporator there.

If I understand you correctly, I shouldn't worry about flushing individual components and hoses until it is all together and then flush. I'm thinking of going with an R12 product/ substitute called Autofrost that seems to have a decent reputation. Have you heard of it?
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