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#1
02-21-2008, 09:52 PM
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W123 Testing the evaporator
Good evening,
Is there any way to test the AC evaporator directly? I have my dash off and would like to determine if my evap is bad now so I can go after it, or at least know that I need to. Im assuming this will involve those AC gauges... My AC currently does not work for an unknown reason, but was converted by PO to R134a in 2005 - so I am assuming it worked at that time. It also has a rebuilt compressor. Are there any good automobile AC newbie guides? I know nothing about the subject and I think Im going to have to learn to get mine workin :-) dd
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------------------------------- '85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit) '82 300D, 'Tex', 228k body / 170k engine ... summer car '83 300TD Cali Wagon 210k, wife's car 
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#2
02-22-2008, 01:21 AM
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Ever seen a 20 year old evap core? I'd replace it along with heater core if dash is off....
ACM seems to be the brand for the A/C
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I'm not a doctor, but I'll have a look.  '85 300SD 245k '87 300SDL 251k '90 300SEL 326k Six others from BMW, GM, and Ford. Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]
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#3
02-22-2008, 10:32 AM
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Gauges can be used anytime to determine if the system is at proper pressure. You need to check for a leak. Go here and buy a sniffer and run it all over the evaporator if it beeps you have a leak and should replace it.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92514 Dave
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1970 220D, owned 1980-1990 1980 240D, owned 1990-1992 1982 300TD, owned 1992-1993 1986 300SDL, owned 1993-2004 1999 E300, owned 1999-2003 1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD 1988 560SL, 100,000mi, owned since 1995 1965 Mustang Fastback Mileage Unknown(My sons) 1983 240D, 176,000mi (My daughers) owned since 2004 2007 Honda Accord EX-L I4 auto, the new daily driver 1985 300D 264,000mi Son's new daily driver.(sold) 2008 Hyundai Tiberon. Daughters new car
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#4
02-22-2008, 03:15 PM
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Also check the "O" rings on the expansion valve. Once I replaced these on my '83, the system is completely leak-free. The original evaporator is made of copper, so should have a long service life. While you're in there, convert it back to R-12- cools much better on a hot, humid day when you really need it, and puts less strain on the compressor.
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#5
02-22-2008, 03:40 PM
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Yeah, I've always heard people say that pulling the dash out is the worst part. Might as well replace it while you have that out.
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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century  OBK #55 1998 Lincoln Continental - Sold Max 1984 300TD 285,000 miles - Sold The Dee8gonator 1987 560SEC 196,000 miles - Sold Orgasmatron - 2006 CLS500 90,000 miles 2002 C320 Wagon 122,000 miles 2016 AMG GTS 12,000 miles
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#6
02-22-2008, 03:59 PM
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Thank you for the replies. I may just go ahead and replace the evaporator then. I wouldn't mind cleaning out my evaporator box too while i'm at it to get rid of the moldy smell. The car is off the road for at least another six weeks.
Main issue I have with just diving in any further is, at least in theory , my AC system is still charged. Is there any way to discharge it by DIY methods - or do I have to limp my car to a shop to get this done? (my system is 134a)
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------------------------------- '85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit) '82 300D, 'Tex', 228k body / 170k engine ... summer car '83 300TD Cali Wagon 210k, wife's car Last edited by dieseldan44; 02-22-2008 at 04:14 PM.
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#7
02-22-2008, 05:40 PM
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Don't quote me but 134a should be safe to discharge into the air. Those little canned air computer dusters are just cans of pressurized 134a. You just have to get a way of safely releasing it.
Now if it was R12, it would definitely be a good idea to get it to an A/C shop to recover it for recycling. R12 is a finite resource these days.
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Dale http://i52.photobucket.com/albums/g1...MG_2277sig.jpg 1990 300D 2.5 Turbo -155k 2000 E430 - 103k 2014 Jeep Grand Cherokee Ecodiesel 4x4 - 11k 2014 VW Passat TDI SE - 7k Bro's Diesel 2006 E320 CDI - 128k Pop's Benz Pre-glow - A moment of silence in honor of Rudolph Diesel
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#8
02-22-2008, 06:55 PM
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IAW federal law if you are a 609 licensed AC tech you cannot release R134a into the atmosphere. It must be recovered. If you are not a 609 licensed Tech, it does not exactly discuss this. And as posted the computer cleaners in a can are R134A.
Dave
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1970 220D, owned 1980-1990 1980 240D, owned 1990-1992 1982 300TD, owned 1992-1993 1986 300SDL, owned 1993-2004 1999 E300, owned 1999-2003 1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD 1988 560SL, 100,000mi, owned since 1995 1965 Mustang Fastback Mileage Unknown(My sons) 1983 240D, 176,000mi (My daughers) owned since 2004 2007 Honda Accord EX-L I4 auto, the new daily driver 1985 300D 264,000mi Son's new daily driver.(sold) 2008 Hyundai Tiberon. Daughters new car
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#9
02-23-2008, 10:16 AM
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Quote:
 If dusters are R134a then Im not going to worry about capturing it. i'm going to stay with R134a too so I have the ability to do most of the service myself. im in MA, so I don't need turbo-charged ever little last bit of performance AC like you Texas guys :-) alright, looks like i'm going to go for the gold here and get the whole evaporator box out for a full cleaning. ill pressure test the heater core and swap out the evaporator too. when I look down from the top vent it looks like the evaporator is new. at least the fins in that middle area don't look gunked up. any way to tell? do the original parts have an MB star on them somewhere? dd
__________________
------------------------------- '85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit) '82 300D, 'Tex', 228k body / 170k engine ... summer car '83 300TD Cali Wagon 210k, wife's car
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#10
02-25-2008, 09:14 AM
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bump -
I purchased a the Haynes 'Heating and A/C' techbook and now this whole AC thing looks much less intimidating. But they did not describe how to discharge an R134a system. Could someone enlighten me on how to do it? It cant be hard. I suspect my system has discharged itself already, but to be sure....
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------------------------------- '85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit) '82 300D, 'Tex', 228k body / 170k engine ... summer car '83 300TD Cali Wagon 210k, wife's car
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#11
04-04-2012, 02:52 PM
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I know this is quite an old thread, but dieseldan, did you ever figure out how to discharge your ac? Trying to look up info about that myself, and can't seem to find anywhere that tells how to do it, only on how to charge the system.
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#12
04-05-2012, 01:10 PM
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I believe the easiest way is to "accidently" find a loose line on the reciever dryer. Those fittings "accidently" work loose with a wrench.
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Sam 84 300SD 350K+ miles ( Blue Belle )
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#13
04-05-2012, 02:37 PM
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there were three HP ratings on the OM616... 1) Not much power 2) Even less power 3) Not nearly enough power!! 240D w/auto Anyone that thinks a 240D is slow drives too fast. 80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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#15
04-08-2012, 01:32 PM
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as 134 is not a ozone depleting gas, according to the EPA, many feel it's ok to dump it, however, it's a MAJOR greenhouse gas, something on the order of 1200 times more carbon footprint than CO2...
I'm just sayin... the proper way, is to have a reclaim/recovery machine suck it all into a tank... PLENTY of the machines are available on craigslist, most come with a tank as well... $50 is what I paid for mine.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!!  1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
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