The AC service ports on this vehicle appear to be on the line that runs along the driver's side fender well past the ABS unit and another one appears to be in a line above the compressor near the engine. Which is the high pressure side and which is the low pressure side?

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Tony

1988 300E Metallic Blue Black/light Gray interior

MBCA Member

The low side port is on the fat line heading back towards the firewall. It is just to the left of and below the nest of brake lines heading to the ABS actuator. The other one is, of course the high side. Hmmm another w124 A/C story in the making..

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

The first line you've described is low pressure (suction); follow it rearward and you'll see it connects with a second line, which in turn mounts to the expansion valve.

And, obviously, the second line you described is high pressure (discharge).

BTW, there is another high pressure port. It is inside the righthand frame rail and heads out to the condenser. Very near the front of the A/C compressor pully. Located on the metal manifold tubing, black in color.

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Jeff Lawrence
1987 300e
1989 300e
1987 BMW 325

The easiest way to identify high and low sides is to remember that between the evaporator and compressor is low side and between compressor, through the condensor to the evaporator/expansion valve is high side.

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

AWESOME! I'm resurrecting a seven year old thread!

I just wanna know if that applies to a 95 e320 as well. low up top close to the expansion valve and firewall, and high side down by the receiver drier up front behind the headlight...correct?

If the system is working and running, the low side line is cold and the high side is hot.

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2012 E350
2006 Callaway SC560

well I just replaced the core and drier and all that jaz am I'm taking it to have it recharged. the only thing is that this place is an audi shop and they haven't done a benz before.

i just hope they pull vacuum on it for an hour or so....

you shouldn't have any problems... last year i did the same for my CE.... did all the work..then let them pull vacuum and re-charge.... that took a big monkey off my back.

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1989 300ce 129k
( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone)

1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it


[/SIGPIC]

Your car has a Japanese compressor anyway so they'll probably do OK.

You can buy a new vacuum pump these days for about $100. Money well spent, I think. You can run it as long as you want and KNOW it was properly done.

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2012 E350
2006 Callaway SC560

yeah they are gonna pull vac and what not. its a nice audi shop, heck they are the guys that ordered all my parts for the job! anywho, thanks for the confirmation that low is up top and high is down, I'm taking it in in about an hour........I've gotta go put the drivers seat in!

A picture is worth a thousand words see # 18 & 20

1. Valve cover
2. Thermo vacuum valve
3. Oil dip stick
4. Air cleaner
5. Fuel injector (first, 1 of 7)
6. That's the line from the coil to the distributor (some people call it a rotor). The distributor sits in front of the engine, under the plastic cover that is oh so close to the radiator fan!
7. the thermostat housing (Benz-LGB).
8. Belt tensioner bolt
9. brake vacuum hose (to assist with the power brakes, no vacuum no power brakes - BENZ-LGB).
10. Timing cover
11. Coolant hose
11a. also coolant hose?
12. power steering pump
13. ABS module
14. ABS lines
15. a/c pressure switch
16. a/c reciever/dryer
17. ballast resistor
18. high pressure a/c line
19. Ignition module
20. low pressure a/c line
21. looks like the cover for your coil

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1996 E320 since 1/16/08, 171K miles as of Feb 2011

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1989 300CE - R.I.P. Dec 29 2007
Other MBs (sold): 1992 300E-24 - 1979 350SLC - 1984 230E - 1990 300CE