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  #1  
Old 08-03-2007, 12:01 AM
Bob's your uncle
 
Join Date: Aug 2007
Location: Charlotte, NC
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Quick AC question

If the pipes/fittings circled in red are missing on a '87 560SL what does that mean? What parts of the AC is not working? -or has the AC been converted to R134?

The second picture if of the engine where the pipes are missing.

Thanks,
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Quick AC question-02eb_12%5B1%5D.jpg   Quick AC question-1812149_15%5B1%5D.jpg  
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  #2  
Old 08-03-2007, 12:32 AM
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Location: Battle Ground, WA
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The large tube is the AC return line. The Copper area with the two fittings that have missing lines is the fuel cooler, the fuel lines have been replaced and not connected to the cooler. The AC system hasn't been altered, but the fuel line routing has.
If you unscrew the blue cap shown in the picture there will either be a quick disconnect fitting or a 1/4" flare fitting. The quick disconnect is for R134, the 1/4" flare is for R12. Depending on the fitting type you can assume which refrigerant the system has.
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #3  
Old 08-03-2007, 07:31 AM
Bob's your uncle
 
Join Date: Aug 2007
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Thanks Richard. Under what circumstances would you not reconnect the fuel line cooler? Since this is on the return I would suspect that reconnecting the fuel cooler would fairly easy to to. Get the two missing hoses and fittings and reconnect them.

One reason that it would not be connected could be that the cooler is blocked. Is that an easy DIY way to determine if that is the case?

Another thing, since the cooler is on the AC return it would only work if the compressor is on, which doesn't happen much, so leaveing them disconnected shouldn't have that great an impact om performance?

Last edited by sgaar; 08-03-2007 at 08:17 AM.
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  #4  
Old 08-03-2007, 08:29 AM
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There are two fuel ine connections near the firewall. As I remember, one line goes over the far end of the driver camshaft cover near the firewall and goes to the fuel distributor. The other goes to the cooler collar. The other line from the cooler goes to the front of the fuel distributor. I think the purpose was to keep fuel from vaporizing at hot temperatures. The theory is that the AC will be on at hot temperatures. Yours was probably routed direct. It has no relationship to the AC function, R12 or R134.
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  #5  
Old 08-03-2007, 09:23 AM
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The fuel line cooler isn't included on the earlier SL models, so the cooler, although very desirable, probably isn't totally necessary. The Mercedes engineers must have run into a hot location that made the cooler desirable. My '82 doesn't have it. It is hard to second-guess why it's not hooked up, but my guess would be that the previous owner found it hard to get the correct fuel lines, not that the cooler had a problem.
By the way, the AC is ALWAYS operational, except when the "economy" or "off" pushbuttons are depressed. (The compressor is engaged for all pushbutton positions except the two on the right end of the row.)
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #6  
Old 08-03-2007, 09:54 AM
Bob's your uncle
 
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Quote:
Originally Posted by Richard Wooldridge View Post
The fuel line cooler isn't included on the earlier SL models, so the cooler, although very desirable, probably isn't totally necessary. The Mercedes engineers must have run into a hot location that made the cooler desirable. My '82 doesn't have it. It is hard to second-guess why it's not hooked up, but my guess would be that the previous owner found it hard to get the correct fuel lines, not that the cooler had a problem.
By the way, the AC is ALWAYS operational, except when the "economy" or "off" pushbuttons are depressed. (The compressor is engaged for all pushbutton positions except the two on the right end of the row.)
This is for an '87 560 SL so I am assumeing that the cooler was operational when the car left the factory which leads me to beleive that someone later disconnected the cooler.

Correct me if I'm wrong, but the compressor is off when the AC is off. When compressor is off there is no circulation of coolant, no condensing and thus no cooling. In most cases when you drive with the top down you would not use the AC anyway.

What are the pro/cons for keeping it disconnected vs. reconnecting it?

On another note; where can you find the shopmanuals for an '87 SL on CD/DVD? I know that you can get the printed manuals from MB's Classic Center for about $35 but for searching the CD might be good as well.
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  #7  
Old 08-03-2007, 11:02 AM
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Hmmm...

I may be wrong with this, but I believe the blue AC port cap is a standard indicator that the system has been converted to 134a. My "other make" cars with original factory fill 134a systems have black caps. My converted cars have blue caps that were installed to alert technicians of the switch from R12 to 134a. There also should be a decal warning of the conversion.

Factory CD ROMs for the 107 are available here for $20 plus shipping.

http://www.classictechlit.mbusa.com/MB/

FWIW,

230/8
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  #8  
Old 08-03-2007, 11:04 AM
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Quote:
Originally Posted by 230/8 View Post
Factory CD ROMs for the 107 are available here for $20 plus shipping.

http://www.classictechlit.mbusa.com/MB/

FWIW,

230/8
I was looking at that and isn't that the printed version?
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  #9  
Old 08-03-2007, 11:20 AM
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Yes, you are wrong... The only time the AC compressor is not running is when the CLIMATE CONTROL system is off, or when the "economy" mode is selected, which is the second button from the right side. The climate control system keeps the compressor running at all times, and adds heat when it needs it to control the temperature. You could defeat this system by unplugging the compressor clutch, but the compressor shaft seal will fail sooner due to lack of lubrication. Keep in mind that this is a Climate Control system, with no "AC" button, only a temperature dial. I looked all this up in the factory manual to be absolutely sure.

Yes, 230/8, you are correct in that all the blue caps I've seen have been for R134 systems, but the only way to be certain is to unscrew the cap and check for a quick disconnect fitting. R134 conversion systems usually have a blue cap on the low side and a red cap on the high side, but my wife's Taurus has black caps on both sides and it's an R134 system from the factory...
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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C
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  #10  
Old 08-03-2007, 12:25 PM
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Join Date: Dec 2002
Location: Visalia, CA
Posts: 379
Ok, a couple of quick things:

As mentioned, the lines go to the fuel cooler. And also as mentioned, someone probably did bypass it due to difficulty/expense of obtaining the correct lines. You might want to look over their handiwork, oft times those who choose this type of repair in order to save a buck or two don't make the best of choices on other repairs.

The A/C compressor is designed to run most all of the time, with the above notations of the Economy mode and the Off position. Otherwise the system operates on the "reheat" theory, where all of the air is cooled and dehumified before being brought to the desired temp.

The color of the caps on the A/C service ports means nothing. They are muck like valve stem caps, and can be obtained in any just about any color or material. Do not rely on them for anything. They indicate neither refrigerant type or pressure (high vs. low). A refrigerant identifier should be used if you have any questions as to what is in the system (it's mandated by law in CA). You should never assume anything, the contents of the system could be R-12, R134a, any number of blends, propane, or air. You should be able to tell by location whether the port is high or low pressure. If you don't know, you should spend a little more time studying refrigeration theory before attemping any D.I.Y. repairs.

Just a few quick notes. Have fun.

MV
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  #11  
Old 08-03-2007, 12:56 PM
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sgaar:

Nope...$20 gets you the CD...wish it was the printed manual.

230/8
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  #12  
Old 08-03-2007, 05:24 PM
Bob's your uncle
 
Join Date: Aug 2007
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Quote:
Originally Posted by 230/8 View Post
sgaar:

Nope...$20 gets you the CD...wish it was the printed manual.

230/8
Looking for manuals for an '87 560SL I get this:

Part Number Part Name MediumUnit PriceQuantity
QL-6510-1277-02 Edition 1988: Passenger cars ... print$39.99

(More here: http://www.classictechlit.mbusa.com/MB/cstmsearch.asp?MYID=1041&SDID=1334&MDID=-1&ENID=-1&catalog_name=Retail )

And they are all printed. No CDs available.
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  #13  
Old 08-03-2007, 05:27 PM
Bob's your uncle
 
Join Date: Aug 2007
Location: Charlotte, NC
Posts: 76
Quote:
Originally Posted by BAVBMW View Post
Ok, a couple of quick things:

As mentioned, the lines go to the fuel cooler. And also as mentioned, someone probably did bypass it due to difficulty/expense of obtaining the correct lines. You might want to look over their handiwork, oft times those who choose this type of repair in order to save a buck or two don't make the best of choices on other repairs.

The A/C compressor is designed to run most all of the time, with the above notations of the Economy mode and the Off position. Otherwise the system operates on the "reheat" theory, where all of the air is cooled and dehumified before being brought to the desired temp.

The color of the caps on the A/C service ports means nothing. They are muck like valve stem caps, and can be obtained in any just about any color or material. Do not rely on them for anything. They indicate neither refrigerant type or pressure (high vs. low). A refrigerant identifier should be used if you have any questions as to what is in the system (it's mandated by law in CA). You should never assume anything, the contents of the system could be R-12, R134a, any number of blends, propane, or air. You should be able to tell by location whether the port is high or low pressure. If you don't know, you should spend a little more time studying refrigeration theory before attemping any D.I.Y. repairs.

Just a few quick notes. Have fun.

MV
The port in question is low pressure. High pressure is on the passenger side in front of the firewall. Anyhow, the reason for these questions is that I just bought the car abut it doesn't get here until Monday. I just noticed when looking at the pictures that the lines were missing.
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  #14  
Old 08-03-2007, 06:00 PM
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sgaar:

This is the technical data manual, not the service manual. Call them and you can order the CD ROM service manual which explains how repairs are done. The TDM has all the specifications for all the models made in that model year.

Different animal, but valuable in its own right.

230/8
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  #15  
Old 08-03-2007, 06:01 PM
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Join Date: Dec 2002
Location: Visalia, CA
Posts: 379
Actually, I wasn't really aware that you had a question about the ports themselves. That was mainly meant as general information in regards to what others had posted. I thought that your question was mainly about the fuel cooler lines and that it just so happened that the lowside port was visible in the same picture. Conversion between refrigerants wouldn't really affect the fuel cooler. Perhaps it's efficiency, but not in a particularly important way.

I suppose I should also add that the fuel cooler is more properly a heat exchanger. It cools fuel and warms refrigerant. During cool/cold weather operation the extra heat from the fuel helps to ensure that all of the refrigerant returning to the compressor is vaporized. Nifty trick, that, as compressors aren't particularly fond of liquid in the suction line.

Good luck with your new car.

MV
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