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  #1  
Old 02-21-2008, 10:52 PM
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Question 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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  #2  
Old 02-22-2008, 02:21 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.

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  #3  
Old 02-22-2008, 11:32 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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  #4  
Old 02-22-2008, 04:15 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  
Old 02-22-2008, 04:40 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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  #6  
Old 02-22-2008, 04:59 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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Last edited by dieseldan44; 02-22-2008 at 05:14 PM.
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  #7  
Old 02-22-2008, 06:40 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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  #8  
Old 02-22-2008, 07:55 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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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  
Old 02-23-2008, 11:16 AM
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Quote:
Originally Posted by dmorrison View Post
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
so, how would i discharge it?

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
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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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  #10  
Old 02-25-2008, 10:14 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  
Old 04-04-2012, 03:52 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  
Old 04-05-2012, 02:10 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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  #13  
Old 04-05-2012, 03:37 PM
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Here is the AC stick thread.
A/C recommendations for the MB vehicles

Charlie
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  #14  
Old 04-08-2012, 04:13 AM
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Haha. I hate when those "accidents" happen
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  #15  
Old 04-08-2012, 02:32 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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