NPI-FUEL

Anybody ever replaced an AC evaporator in a SL300 ('90) ?

AC is blowing OK, just not cold anymore. Dealership diagnosed evaporator as being leaky and is willing to replace for $4,000. They apparantly replace quite a few of them ...

Dealership tells me the whole dash has to come out. I'm not afraid of DIY but would need some type of manual, instruction on how to take the dash out without too much damage. Any pointers appreciated, TIA,

Rudi

stonechip

I had my evaporator replaced 5 years ago for $ 2,900 by an authorized MB dealer.

It takes approximately 8-10 hours to completely remove the dash board –the evaporator is in under the passenger’s dash airbag system. The evaporator is just one of about 15 different parts that are also replaced including several seals, and hoses. A very delicate job.
It's a repair job that I would highly recommend to have an authorized MB shop perform.

After my evaporator was replaced I experienced electrical problems; the dashboard was removed, several wires were not properly seated during reinstallation and a headlight overload protector wire was pinched during the reinstall of the dashboard, all covered under the warranty. No other A/C problems since then.

a2aa

I did my 94 sl 500's evaporator last september 2003- It took me 26 hrs to do. One thing I would suggest is to replace the defective evaporator with an american made replacement unit using copper tubing. The original design was made of all aluminum w/c apparently is prone to corrosion and leakage. I also replaced the heater core due to it being in the same box as the evaporator and all the vacuum actuatros - while you are in there.

I used a 20 dollar label maker to "mark" my path so that I may be able to return to sanity when time to reasssemble the whole thing. Do check if the a/c is working before assembling everything back. You can do this by connecting the airbags before you reconnect the battery. I got my evap @

www.autopartstreet.com

This after market unit is also hundreds less: @ $212 compared to $800-900 for the behr/mbz unit-


My total cost : $925- this cost literally replaced all a/c components under the dash ie:evap,heater core, 7 vacuum actuators

good luck

eabul

When i replaced my Evaporator in Mercedes Autorized dealer, he told me that the evaporator has a 7 years warranty, which in my case my car was 6 years old. All parts were free, and i only paied for labour charge....

there are some majour parts in the car that has long warranty period...

When looking for a goodwell job, u need to have a good history for you car maintanace with an othorized mercedes dealer...

MB Germany did check the maint. history of my car and agreed to change the evaporator for free....

a2aa

NPI-FUEL

I tried to e-mail you my "diary" but your e-mail addy didn't accept my reply..Do you have another e-mail address??


a2

a2aa

hey guy,

Are you done with your evap project?? Just wondering...

gpniceville

Just a comment, and I do about 4 evaporators a week including W210/W129/W124/W140/W201, and YOU WANT TO STICK WITH OEM. As far as copper, which someone mentioned, corrodes, aluminum does not. Aluminum also transfers heat better. My first SL took 11 hours, down to 7 hours now. Best Advise is to know how to remove the dash, and everything under the hood in the cowling where the windshield wiper is to get to the expansion valve and heater core hoses.

Good Luck

Greg

a2aa

"there are a number of possible reasons why you would see an increase in the failure rate of aluminum automotive airconditioning evaporators. It may be that the vehicles are operating in an area with a corrosive air pollutant which causes an increase in corrosion. Sulfur dioxide is an example of such a pollutant. It dissolves in the condensation on the evaporates and forms sulfuric acid. This quickly corrode the aluminum evaporator.

Another factor which may be part of this problem are the changes occuring in the manufacturing process of the evaporators themselves. Several changes are being made at this time. The first is that chromate coating are being phased out as corrosion inhibitors on aluminum evaporators as part of an industry goal to eliminate hexavalent chrome from vehicles." corrosion.com

...so why again do you change out 4 aluminum evaporators a week? Aluminum evaporators=job security

Apparently there is a reason why you are doing 4/week. And to actually put the same defective component back in ......is thinking backwards

my 0.02

gpniceville

Because I am a Mercedes Benz Technitian. There has been a bad rash, over the years of bad evaporators, I have never replaced one on a W123 or a W126, so why did they not stick with that design, and I like your answer, Mercedes Benz job security. But someone mentioned copper, copper corrodes bad, it is just used because of abundance and electrical properties, obviously not with an evaporator. I have never seen a corroded aluminum evap, a little dirty but no major corrosion.

Best Regards...

Greg

a2aa

so, with the abundance of leaky aluminum evaporators, have you examined any of them to actually try to determine the cause of the failure? And another thing, what IS the ratio of aluminum vs. copper in terms of failure rate - in your shop experience?

gpniceville

I/We do not use copper evaporators. I do hear that they are better, but I am not in the mood to try to bend a copper one to make it fit. Every time I have gotten an evap that is not a Behr, I have had to make several adjustments to the lines that run through the firewall to the expansion valve. I try to make the adjustments comparing the two evaps, but that only helps the major deformities, and while working in such cramped quarters, behind the master cylinder, it sucks using aftermarket. If you don't want to replace your evaporator every five or six years, buy a Honda.


Best Regards...

Greg