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W123-TECH Air Conditioning - Freon - Conversion

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Grey Ghost's picture
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I have asked my garage to replace my compressor and change to R-134 without replacing any of the other components. My rationale is that I KNOW the compressor is in the ninth inning and I also know that when they go, they contaminate all of the other components. I'm also trying to avoid a multi-$$$ job since I'm doing 30,000 mile service at the same time. Any thoughts on this strategy?

p.s. the a/c still works (weakly)

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My experience with other cars has been that this proceedure will work sometimes. To get 99% assurance that the conversion will be successful, replace the receiver dryer and use ester oil not pag.
Joe

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Joe - that makes sense...receiver dryer and expansion valves are about $45 each and Performance Products will only warranty their rotary compressors if these two parts are also purchased & installed

what's the diff between ester and pag oil?

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ester versus pag oil

Without going into technical details, ester oil is somewhat compatible with with the remenents of the oil used in r-12 systems. PAG oil will not mix and will cause premature failure of the compressor if any r-12 oil is present in the system. As we all know it is virtually impossible to get all traces of the r-12 oil out of the system unless the entire system is replaced. Some entrained oil in the condensor and evaporator will remain even after thorough flushing. I hope this helps.
Joe

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Joe - thx for the response. Once one has replaced the compressor, receiver/drier and expansion valve, the rest of the A/C components are mainly hoses, aren't they?

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air conditioning

Thats true, hoses, evaporator and condenser. We have not had trouble with the hoses for a few years. The seals also seem to be holding better on the newer cars. When we first started 134 conversions, the hoses were not compatible with the smaller molecular size of r-34 and it would permeate through the hose wall. The seals were also a problem but everyone has been using the green synthetic seal for several years now. This is sort of a rambling answer I hope it gives you the information you need. If your car is 82 or newer I wouldn't think you would have hose problems. Keep in mind I am not familiar with Mercedes genealogy.

Anonymous
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A/C Repairs

Speaking of A/C units....two weeks ago I started to hear a noise from the engine compartment that did not sound right. I was headed to Church services and could not keep the Lord waiting so I continued. After Church I decided to drive the three miles to my home to checked for the noise and found the bolts that hold the clutch pully to the clutch flange had loosened causing the ruckus. The pully, now being out of alignment pinched the wires to the clutch which shorted and blew the fuse eliminating the A/C and the blower fan operation. The pully was realigned and the bolts were secured. After repairing the wires the clutch contacts were repositioned and the blown fuse was replaced. I think the Good Lord was on my side that day because everything went smooth without hang-ups.

Anonymous
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New 123 owner/A/C Conversion

I just purchased an '83 240d with 26,400 miles. Any tips on getting the AC conversion done?

thanks Wendell

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Maxbumpo's picture
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Sure - don't do it. The system was designed to use R-12, and will work best with that refrigerant. R-134 performance will fall short, generally due to the expansion valve. For most vehicles, after-market expansion valves are available that are designed for R-134, but I have not seen one made for MB's.

If the price of R-12 puts you off, there are alternatives like Freeze-12, that are less expensive but more likely to deliver adequate performance.

There's also a great deal of discussion about the different refrigerant oils, mineral based vs. PAG, horrible conditions like 'Black Death', lose of R-134 via the original rubber hoses which are not 'barrier type'.

When I bought my 190D, a major selling point was that it still had R-12 in the system, had never been converted.

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Max Dillon
Charleston SC
'87 300TD, 334k miles (head is off, getting ready to install a different used head...)
'95 E300 Diesel, 348k miles (daily driving duty)
'73 Balboa 20

Anonymous
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A/C Conversion

Thanks for the input. I think I have a no freon in the system situation. I have not checked for sure but the prior owner said it was not cooling and he took it to his dealer in 2003 for a check. The repair receipt shows they looked at it and suggested a conversion..... So, I am assuming it won't cool next Summer. I don't know if anyone has old 12 anymore so I am thinking a conversion is my only option.

Wendell

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shadetree's picture
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1984 300DT
1984 230E
A/C conversion

Back about 1996 the high pressure lines failed on my 84 300D and lost the
R-12 refrigerant charge. So removed the lines and took them to a shop
here in the Springs and had a new set fabricated using the metal portions
of the old lines since the service valves were installed in them.
Since the Early 1980's and before while in the Army HVAC was one of my specialties for Military refrigeration and AC equipment. So when the thing came
on about the phase out of R-12 systems I sure had it drilled into me about
all the horrors of mixing etc. regarding conversions by the DOD people.
About the time my car problem happened the Army/Air Force exchange
service stations started selling a conversion kit that required nothing
to do except insert a solution in with the R-134 charge without changing
the refrigerant oil or anything. This particular kit used a pag oil along with
the solution that would make the old and new oils work together.
Since then I see that the Interdinamics (spell?)ID company makes and sells
similar conversion kits in about every auto parts store everywhere.
I did my conversion back about 1997 and have had no problem since.
In fact since I have been the only owner of the car and know the history
and maintenance I didn't even bother to change the dryer or expansion
valve either. Now I do know that most any auto parts place that sells
one of the AC compressors will not guarantee unless the dryer and
expansion valve are changed at the same time. And thats sure a good
idea expecially if a repairman does not know the history of the vehicle
and is doing the job for a costumer instead of himself.
Regards,
Chas Mattix

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Charles E Mattix

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I'm with Meade. Keep it R-12. It is available and the cost of keeping it in R-12 shouldn't be much more than converting. I do not agree with using a refrigerant other than R-12 or r-134 though. I'd not even consider Freeze 12 or any of those refrigerants.

Len

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Len

'59 220S cabriolet

'83 240D 348,500 miles original owner

'99 E300D 170,000 miles

'03 SLK320 27,500 miles

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I did the R134a changeover a few years ago. I replaced the drier bottle, some o rings, and expansion valve if my memory serves me correctly, I also had to drain out the old stuff and hookup a vaccum pump to the system.

I did this a long time ago and dissapointed with it. It doesnt cool as well as R12, dont get me wrong, it works, but just not as well.

I have heard lots of good things about Freeze 12, so I would give that a shot before changing over to R134a. With freeze 12, you dont have to change anything, if it doesnt work for you, oh well, THEN change parts and switch to R134a.

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A/C Search for r12

Thanks for the input on this. I will be on the search for an R12 source here in Dallas. Any tips would be appreciated. I would like to avoid the conversion if at all possible.

Wendell

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I think you've made a good choice. You can find R12 on ebay. I bet most AC shops still have it too, but they'll make you pay dearly for it.

Len

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Len

'59 220S cabriolet

'83 240D 348,500 miles original owner

'99 E300D 170,000 miles

'03 SLK320 27,500 miles

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r12 Search

Hey,

Any tips on how much R12 I should be getting if I go the ebay route?

thanks Wendell

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I think the R12 on ebay is Freeze 12 or a similar type of R12 subsitute, dont you have to have a license to purchase the old style/original R12?

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I don't know for sure, but I'll bet that it is less than 2 lbs. If you get a 5lb can or 10lb can, you'll be set, and price/lb drops with bulk purchase.

Becareful of evilbay R-12; some is recycled from junk cars and not properly filtered/purified. There is a whole EPA certification process that legitimate sellers will go through, and they will be able to supply some sort of receipt or seal or something for each bottle of 'virgin' R-12. Of course, you'll pay a premium, but you'll know that you're getting what you pay for. Also, in order to purchase, you really should also get the license for it; there are courses available on-line, with the test, that will license you for ~$20 or so.

You'll also need a vacuum pump, set of gauges, accurate scale (new charge is metered in by weight, not by pressure like R-134). Lots of investment in order to do this work yourself, but if you've got a few cars to maintain and some big problems to solve, you might come out ahead $$wise. Check out pawn shops for used equipment. Personally, when I've got to have mine serviced, I'm just going to find a good shop that I trust and pay them to do it.

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Max Dillon
Charleston SC
'87 300TD, 334k miles (head is off, getting ready to install a different used head...)
'95 E300 Diesel, 348k miles (daily driving duty)
'73 Balboa 20

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r12 is much better, as is mineral based esther oil.

usually a vacuum pump comes in handy on an older sytem for getting all the garabage out.

134 performance will not be as good as r12, but it can be done. just change the dryer, o-rings, and make sure your expansion valve opens.

I have a lot of wisdom about ac systems i wont share, though, becuase you'll all think i'm a lunatic (:

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Pierre Hedary
...happily servicing vintage Mercedes-Benz in sunny Florida...
1972 280SE 4.5 252K
1970 280se 3.5 coupe 108K
1971 300sel 4.5 121K
1991 420SEL TMU, but looks brand new!
Mercedes technical advice: 407 765 2867

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Pierre,

We already know you're a lunatic like the rest of us 123 fanatics. Do share your AC wisdom!

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Max Dillon
Charleston SC
'87 300TD, 334k miles (head is off, getting ready to install a different used head...)
'95 E300 Diesel, 348k miles (daily driving duty)
'73 Balboa 20

Anonymous
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Air Conditioner Hissing Noise

My 78 300CD air conditioner won't put out cold air. There is a hissing noise in the dash. Any suggestions?

Thanks!

Jonathan Weaver
Playa Vista, CA
Grandpa's 1978 300CD 158K

Anonymous
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a/c

Hi Is the compressor engaging,did you check thepressures,ifall is inoder ex;25-30 ON THE LOW AND 225-350 on the high and fans commong on,you could have a vac ,or venting problem in the dash,if on the other hand your pressures are not correct,you might be having a problem with the expansion valve be ing wide open and not allowing for a boil down in the evaporator.Joeym

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Thanks a bunch. I don't think the compressor is coming on as I don't hear the "click" like I usually do when I flip the switch. Belts seem ok. I will check the vacuum line first, then test the pressure, if the pressure holds then I will likely replace the compressor, the drier and expansion valve. All three seems a little much, but I have heard if you are replacing the compressor then the drier and expansion valve should probably be replaced also.
I will go for the yellow vacuum lines by the oil filter, any other place to check for vacuum leaks without pulling the car apart.
Thanks!

Anonymous
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a/c system

Hi Ithink there should be a green hose going to the a/c control switches and another one,one is master relay and the other one is systems relays.I would check with the Doc on this.Its going to add up if you replace all these items plus freon ,oil ect.I would make sure the power circuit is ok before you replace anything.Joeym

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Thanks a bunch, I will check this out and get back to you.
jW

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Re-charge AC on 300D

The AC will not cool down. Is a recharge something an ordinary AC place can do on my 300D or do I have to drive 100 miles to a dealer to do it? :rolleyes:

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Tough to find anyone who will do an R-12 recharge these days. You may have to bite the bullet and convert to R-134a, about $800.

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gerkebi wrote:
Tough to find anyone who will do an R-12 recharge these days. You may have to bite the bullet and convert to R-134a, about $800.

Don't Do IT! R-134 will never cool as well (you may not notice in MN) because there are no R-134 expansion valves for the 123 series, and the rest of the system is designed for R-12 not 134.

Take the time to find a shop that will service and recharge with R-12. Cost per lb is much higher, but cost of R-12 is much much lower than $800 (should be like $30/lb or so, and your system probably needs a little over 2 lbs).

No need to go to MB dealership, just find a shop that works with R-12.

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Max Dillon
Charleston SC
'87 300TD, 334k miles (head is off, getting ready to install a different used head...)
'95 E300 Diesel, 348k miles (daily driving duty)
'73 Balboa 20

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First of all make sure your car hasnt already been converted to R134a. How long have you owned this car? If you just bought it, etc. Then look where the charging valve is. If it was converted, you will see a blue color cap and an adapter has been screwed on.

If that is the case, then you can just buy some R134a and recharge it yourself. Let me know and I will give you the procedures.

But yah Max bump is right, I dont recomend conversion because it doesnt cool as well as R12. There still is ways to get R12 (for a DIY), but it is expensive and requires a license to buy.

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AC Options

car 1 300D:
okay folks, I MUST HAVE AC! car back from the mechanic (no charge) found leak out of the compressor... did not do repair due to cost. he states that the system needs a complete rebuild/replacement. i need to do this as its my daily driver. his quote for all parts and labor was 1400 - ouch. right now i'm losing a 1/2 pound per day of r134, should i just keep charging? should i bite the bullet at some point when i have money, or are there other alternatives? any input appreciated.

Car 2 300TD: took to get R12 charge and the folks said there was no leak and the R12 was full, yet they were unable to say what the problem was. they checked the compressor and evaporator and thought that they were fine. any ideas? i did not take it to MB mech, it was just a refrigerant place, is there a venting or other issue that may be a relatively easy fix, any ideas?

PS: **** its hot in Little Rock

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Tyler,

What you are experiencing with the gold sedan is called, "storage related issues". Anytime a car has sat in some guys garage for years and then is ran again will experience all sorts of problems.

Tires dryrot, belts crack, A/C, power steering, water pump seals dry out, moisture gets in the fuel system, etc etc. I can write a whole article on it. I have experienced this myself because my 123 sat in the garage the first few years I AND the previous owner had it and same with the Rolls Royce.

On the 123 I had to rebuild the A/C system, change the water pump, and some nick nacks. Then it runs great.

1/2 lb of freon leak PER DAY is a very serious leak, considering these cars hold roughly 2lbs of R134a in the system altogether.

Do you have an itemized breakdown of what your getting for $1400?

Keep an eye on the water pump seal too...

On your wagon, the sight glass is a little dirty, but I could have sworn I saw bubbles. But then again it was so hot around noon, I remember seeing stars too :D

If all those things the A/C tech checked out are fine, then you might have to take it a mb tech. There is only so much diagnosis you can do over the internet. It could be a faulty pushbutton unit or temperature wheel too, there is also a temperature sensor on the center of your dashboard.

Since both your cars are the same, you can swap the units and see if it makes any difference.

Anonymous
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itemized breakdown

the mech made me a breakdown, but he was closed by the time i picked it up. my sense was that the parts were all under 500 and labor was the biggest charge. i did a bad thing, but it seems to be helping, i added some "ez chill" sealant (12.99) and that has slowed the leak tremendously. i figured if i had to replace stuff anyway, i might as well try a 12.99 solution to see if i can limp thru the summer.

car 2: i have yet to have it checked out, so no word on that.

thanks for your help Johnson, i have too many other things to pay for so i may have to "sweat it" for a while!

cheers,
tyler

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Hi Tyler,

Its cool, I can give you some advise and you can follow it and might be able to fix or help it some.

If my memory is correct, BOTH your cars have the same pushbutton control units right? You can easily and quickly "swap them" for a few days, and see if that fixes the problem in your maroon wagon.

The wood panel just pulls off, then there is 2 phillips screws and two wiring harness on both sides. After you have done it a few times it shouldnt take you more than 5-10 minutes each car to remove and install it. This way, you can try to narrow down your problem in your wagon.

As far as the gold sedan, that sounds about right. Labor is expensive because its a pain in the rear, I wouldnt want to change my compressor again if I dont have to.

Maybe have the mechanic change the compressor and you change and charge the rest of the system, this should save you a considerable amount of money?

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Just make sure you dont have a leak in the evaporator.
Thats the coil inside your car.
You could be doing yourself and your passengers some real harm if you ingest freon.
Dont mess around with any leak, get it repaired!

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