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First AC Repair- 2000 ML320 Expansion Valve O-Rings
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tomandjerry00
New User
Jul 18, 2012, 12:07 PM
Post #1 of 4
(7090 views)
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First AC Repair- 2000 ML320 Expansion Valve O-Rings
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My first post here!
So I inherited a 2000 ML320 that has been used as a work truck its whole life a few years ago. Last year the AC went and after a $780 quote to repair it and so many 100+ degree days, I decided I was going to tackle the problem myself. The shop said it was leaking at the expansion valve, probably the o-rings, extremely common for these trucks. My plan to try to repair this as cheap as possible (I plan to sell in next year or so) involves:
I purchased a 2.5 CFM Vacuum Pump, AC Manifold Gauges, couple cans of R-134a and a 382 piece nitrile rubber o-ring set from Harbor Freight over the weekend. I know its not the best quality, but hopefully it will get the job done. The
1. vacuum test system to ensure there really is a leak
2. replace expansion valve o-rings (can I just size up the rings with ones in my kit or do I need to buy a specific o-ring kit?)
3. hold at vacuum for 30 minutes to ensure moisture gone and no leak
4. refill with 1.7 lbs of freon (measured by correct pressure at ambient temperature) with the AC on high
Does this sound right? Should I add oil (more than is just added to the freon)? If so, how much and which kind?
The system has been open to the air for over a year, is it crucial to replace the dryer (I know not expensive, but a hassle to replace) or can I get away without it?
Any other questions or suggestions? Thanks a lot!
2000 Mercedes ML320 3.2L V6 with 96k
2000 MB ML320 98k
1987 Chevy Corvette 68k
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 18, 2012, 12:46 PM
Post #2 of 4
(7062 views)
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Re: First AC Repair- 2000 ML320 Expansion Valve O-Rings
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Slow down sport before you blow up this system. I strongly suggest you get help ESPECIALLY for a first time. It's been down a year +/- so may require flushing out oil which could have become acidic which could quickly rot items out if not already IF AIR was getting in and out of system over enough time and that's enough time.
Read this link which is up top for just basics.
http://autoforums.carjunky.com/..._A/C_SYSTEMS_P45460/
You absolutely need to be able to weigh in the exact charge once you are at the point of believing all is fixed and ready oil amount to be determined and any charge weight listed under hood on a sticker.
Said by a friend who teaches this "The tuition of learning A/C the hard way is very expensive" meaning this could cost you tons more with a mistake so beware.
Do understand that mega thousands in equipment is needed on many not just gauges and a can tap. No additives other than what it calls for, for products.
Come back after reading that above and see if you really want to do this alone or with a pro the first time to avoid nasty mistakes,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Jul 18, 2012, 1:14 PM
Post #3 of 4
(7043 views)
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Re: First AC Repair- 2000 ML320 Expansion Valve O-Rings
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The idea that those O-rings are actually the problem is just somebody's total wild ass guess that I would bet a bunch on isn't even the problem with the system. O-rings are never the whole problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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nickwarner
Veteran
/ Moderator
Jul 18, 2012, 2:39 PM
Post #4 of 4
(7027 views)
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Re: First AC Repair- 2000 ML320 Expansion Valve O-Rings
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With the guys on this. You said the guy assumed it was o-rings but doesn't sound like a complete diagnostic was done just a quick look. You must know the exact weight of the charge you are putting in it. Pressures mean next to nothing when you are filling it up. Please tell me the 134 you bought isn't the crap with leak sealer in it which is called a Death Kit by us in the trade for good reason. Its not good at sealing leaks but great for adding a grand to your repair bill.
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