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Discussion Starter #1
'93 300e, 2.8, 118,000 miles. Everything seemed to work OK with heat all Winter but it's not blowing cold when the A/C is on. The dealer wants something like $250 for a "flush & re-fill"...yikes! Goodyear service want's $54 for a performance test (leak check, compressor function check etc.). I think it's $5/lb for R134a re-charge.

1st question, how likely is it that a re-charge will correct the problem? I guess the real question here is...should I brace myself for a big expense if it's the compressor? And, how common is compressor failure?

2nd question, if it's not the compressor or the need for a re-charge, what else would cause the problem?

3rd question, is there anything about a Mercedes A/C system that's unique such that a Goodyear Center couldn't diagnose & correct?

Your feedback/advice/help would be appreciated.
 

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Benz 260E and others
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how likely is it that a re-charge will correct the problem?
It really depends on the size of the hole by which you are loosing tour R134.
The dealer wants something like $250 for a "flush & re-fill"
Walk, look somewhere else.
if it's not the compressor or the need for a re-charge, what else would cause the problem?
Could be as simple as a leaky a/c line,or as major as an evaporator. (mega$$)
A professional diagnostic is the first step to the cheapest repair. Don't throw parts at it.
 

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'93 300E 2.8
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Proper diagnostics starts with the mechanics putting a dye into the A/C system. This will help them detect leaks and determine the extent. Simply topping off the system is like filling your tires every few hours instead of plugging the leak.
 

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1992 MERZ 400E
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wadman - 4/4/2005 3:57 PM

Proper diagnostics starts with the mechanics putting a dye into the A/C system. This will help them detect leaks and determine the extent. Simply topping off the system is like filling your tires every few hours instead of plugging the leak.
good analogy
 

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Why did the dealer tell you it needed a flush and recharge? A/C systems are sealed systems, so recharge should alwised be followed by replacement of the leaky part, as well as replacement of the reciever/drier or accumulator which keeps water from contaminating the system. If the wanted to flush it, what was blocking the system? It sounds to me like the found unusualy high pressure on the high side of the system which indicates a blockage. But were talking about a sealed system, so where did the blockage come from? Probably from the system itself, as when compressors go they tend to send metal filings throught the system. However I would try to get more detail from the dealership, or another professional diagnosis, as I have on rare occasions seen expansion valves/blocks/orrafice tubes/ get blocked just because somehow a something did get in the system and their filter caught it. If that is the case the flush, replacement of the part (generaly pretty inexpensive) and recharge will work. But you already got some good advice. Get a profesional diagosis from someone who will explain what the hell I just said, and how it affects your car, because benz a/c systems arn't cheep. Alas and alac, I have to replace mine too....
 

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'96 sl500, 87 300td
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"Simply topping off the system is like filling your tires every few hours instead of plugging the leak."

If your in the US continuely topping off is illegal.
 

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1989 300 TE
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My exeriance with a few cars has been the evaporator. It is so expensive because it is behind the dash. So the dash has to be taken out and put back in, according to mechanics. I hope that is not he problem. Last season did it blow cold just not ice cold. Maybe not very cold if the car was left in the sun in the middle of the day? Is so, it is probably the evaporator.
 

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95 E300D
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Lots of similar experience with mine

If its not blowing any cold in my experience more likely a control problem than recharge needed. Lots of generalist A/C shops offer recharge as its easy for them to do and they make good $$$. In my experience you need a recharge when its blowing cold but not cold enough. Get them to check your hi and low pressures , if they look right then no recharge needed.

Much more likely a control problem of some sort. I think compressor failures are also relatively rare (thankfully as they cost $$$$$$$$$$$$$$$)

the control systems are complex but have some common failure points. the most recent one I have had (on my 1995 E300D was that the A/C control unit (behind the controls in centre consol) was not sending the signal to call for the compressor. I have simply installed a £2 black switch under my dash which when flicked sends this signal. Hey presto as much cold air as I want and avoiding an expensive controller replacement.

The only tools I use are a digital multimeter. If you are competant with one there are loads of posts on here and Mercedesshop.com dealing with fault finding of a/c control. Frustrating but satisfying if you can avoid unecessary expensive parts replacement.[^]

If its the same as my E300D (your responsbility to check!) there is a pressure switch with terminal and two connectors on just to the right of the belt at the front of the engine. When the a/c is calling for cold these contacts are grounded, this then sends signal to A/c relay to fire up the compressor. If thats the case then by grounding them yourself you can see if the comp fires up. (NB there may be differences with gassers from diesels so I take no responsibility I can only tell you what worked for my case)

There are tons of posts on this and mercedesshop.com dealing with these kind of problems if you use the search facility. also the CDs have some basic checks on them you can do - thats how I sorted mine.

In my experience any generalist A/c or even many MB techs who dont do much A/c work wont be able to help much. You need an MB tech who is also very experience on A/c fault diagnosis to be any good. I have not found one myself other than on these forums.

let us know how you get on
Keith
 
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