My turn for the Evaporator Party - PeachParts Mercedes-Benz Forum

brewtoo · #1 01-13-2007, 09:41 PM

1990 124 300E. AC won't hold a charge. Significant leak.

I've been told that the definitive confirmation for the leaking evaporator is to remove the blower motor and look at the evaporator. I did. The photos are below. You can see that one side is nasty and oily with lots of crud stuck to it. The other side is clean. Does anyone agree or disagree that this evaporator is leaking?

Of course, MBUSA told me awhile back that they never heard of a leaking evaporator in one of their cars so if mine is indeed leaking, it will, I guess, be the first one ever to leak. Just like the upper neck on my radiator was the very first one that ever broke off.

Everything is starting to look so old in there, I wonder if I should even do this job. It's the challenge I suppose. And there's no car payment. That's nice. The car still runs great and the general public doesn't even know it's 17 years old. I think these 124s still look good. And of course, it would cost as much to have this done as the car is worth. Probably more. OK, I've had this car a long time and I still love it.

So, a couple of questions before I start the Big Project. Should I just leave the blower motor out and proceed, or put the blower motor and wiper motor and all those parts back together first, before I forget how they go together? Any advantage to having the blower motor out already?

Is it better to remove the front seats or leave them in place?

Is it better to leave the car flat on the ground or to drive it up on ramps in the front to elevate the work area a bit?

Any other comments or suggestions? Did anyone ever do a complete DIY on this job?

Which evaporator is best for a replacement?

What questions have I forgotten to ask?

Thanks

#2 01-13-2007, 10:50 PM

If it isn't leaking now, it will. I assume you did this effort as a result of insufficient cooling or none at all.

Replace with an ACM evap that has the expansion valve attached.

Replace receiver drier and make sure your pressure switch on the drier is the red one or you need to replace that at the same time. I have an extra on if you wish to purchase.

My water hoses were a bit difficult to disconnect, but I removed battery to get better access and got it. I ended up taking the battery tray out and cleaning and repainting. Ever read the book "If you give a pig a pancake"

Order a oring kit for your heater core and replace the o-rings as an extra preventive maintenance.

Yes take the fan out to help you remove the box.

Leave the seats in place.

Replace all the vacuum pods while you have the dash out.

Get the printouts from the CD for all steps.

Take digital pictures of every screw you remove, because there are probably 6-7 different types.

There is a caution on removing the leg room flap arm so the plastic piece is not broken.

Everything is just like the book says, straight forward and no MB tools or MB 40 hr training required.

Inspect the shifter bushings when you disconnect the speedo from the tranny.

Put a few drops of ATF on the fan motor bearings while it is out.

Replace cabin air filters.

Use a pry bar like a Super bar to release the box from the firewall

You will need to replace the weatherstripping around the evap box. Cannot get this from MB. I went to Lowes. I think I used 3/4" wide and maybe 1/2" thick. I would not use plumbers putty as the sealer as it is not intended for plastic and non-stainless parts (unless you find a less acidic type). I used silicone based caulk - little messy if you aren't careful.

I never found the plug for the center vent dial light, so I cut the wire and reattached.

There are a lot of plugs to disconnect, so make sure you reconnect them all. I had forgotten the cigarette lighter and I had to remove the console again to find it.

I am sure I left something out, but plan well and take your time.

PS I have just completed mine and I think I might have damaged my ignition switch as a result of not removing it per the instructions. See my post on my fan acting irratic.

http://www.peachparts.com/shopforum/showthread.php?t=176064

Olin

Bruno_300TE · #3 01-14-2007, 10:32 AM

Hi
I did mine about three months ago. Olin made very good comments already. The job is not that difficult, but time consuming (22 hours). BTW, everyone will be impressed after you show them a pic with everything disassembled. The car is better left on the ground. I'd leave the front seat in. But removing the steering wheel helps. This is also what the manual recommends. I took pictures from the vacuum lines and how they are connected. I screwed the fasteners back to their place where possible or attached them with tape. Be careful when disassembling the heater box, there are some clips and plastic that can break.
Good luck, Bruno

J.HIDALGO · #4 01-14-2007, 12:36 PM

The only thing I have to add is: use zip-lock bags to label and separate your bolts and smalls parts I would check the compressor and old the AC lines since if the evaporator goes, the compressor is not far behind (do a search on black death). I did not remove the steering wheel, I just extended it as far out as it would go...same thing with the seats, bring them as far back as they would go...

brewtoo · #5 01-15-2007, 02:13 PM

I've found this procedure to be like dealing with a hundred little jigsaw puzzles. As I go along, I am always impressed with the engineering expertise that went into this car. Like a fine watch.

Anyway, this little puzzle I have not figured out yet: See the piece of ductwork in the photo with the yellow "X" on it? After you remove the one screw in the floor, how do you get that out?

Just curious, has anyone experienced a failure of their replacement evaporator?

Thanks

david s poole · #6 01-15-2007, 05:48 PM

carefully,you have to make old brittle plastic give just enough to get it out. going back is the fun part.

#7 01-31-2007, 07:58 AM

Quote:

Originally Posted by Smoke124

If it isn't leaking now, it will. I assume you did this effort as a result of insufficient cooling or none at all.

Replace with an ACM evap that has the expansion valve attached.

Replace receiver drier and make sure your pressure switch on the drier is the red one or you need to replace that at the same time. I have an extra on if you wish to purchase.

My water hoses were a bit difficult to disconnect, but I removed battery to get better access and got it. I ended up taking the battery tray out and cleaning and repainting. Ever read the book "If you give a pig a pancake"

Order a oring kit for your heater core and replace the o-rings as an extra preventive maintenance.

Yes take the fan out to help you remove the box.

Leave the seats in place.

Replace all the vacuum pods while you have the dash out.

Get the printouts from the CD for all steps.

Take digital pictures of every screw you remove, because there are probably 6-7 different types.

There is a caution on removing the leg room flap arm so the plastic piece is not broken.

Everything is just like the book says, straight forward and no MB tools or MB 40 hr training required.

Inspect the shifter bushings when you disconnect the speedo from the tranny.

Put a few drops of ATF on the fan motor bearings while it is out.

Replace cabin air filters.

Use a pry bar like a Super bar to release the box from the firewall

You will need to replace the weatherstripping around the evap box. Cannot get this from MB. I went to Lowes. I think I used 3/4" wide and maybe 1/2" thick. I would not use plumbers putty as the sealer as it is not intended for plastic and non-stainless parts (unless you find a less acidic type). I used silicone based caulk - little messy if you aren't careful.

I never found the plug for the center vent dial light, so I cut the wire and reattached.

There are a lot of plugs to disconnect, so make sure you reconnect them all. I had forgotten the cigarette lighter and I had to remove the console again to find it.

I am sure I left something out, but plan well and take your time.

PS I have just completed mine and I think I might have damaged my ignition switch as a result of not removing it per the instructions. See my post on my fan acting irratic.

http://www.peachparts.com/shopforum/showthread.php?t=176064

Olin

The first sentence in the quote above is INCORRECT! Not ALL 124 evaporators will leak. Yes, this is most definitely a terrible achilles heel of the 124 MB, but that DO NOT ALL leak or eventually develop leaks. My 88 300E still has the original evaporator and it is still tight. I have had and repaired other leaks and at those times it was difficult to keep from assuming that the problem was the evaporator but it was not.

One time, the expansion valve was leaking and the other time the condensor was leaking.

DO NOT replace a 124 evaporator without CONFIRMING that it is leaking. Use a sniffer and UV dye both. BE SURE!

brewtoo · #8 01-25-2007, 12:02 PM

How much oil should I add back to this system? Replacing evaporator, expansion valve and receiver/dryer.

Bruno_300TE · #9 01-25-2007, 12:31 PM

40ml for the evaporator and 10ml for the receiver/drier. This is for part exchanges. An extra 10ml is added when refrigerant (and some oil) was lost due to a leak. Total volume of the system is 120ml (4 ounces).
Bruno

Kebowers · #10 01-27-2007, 01:20 AM

External corrosion due to mold. Mold will form corrosion 'cells' that will 'eat' right through the aluminum--probably where the 'South has aluminum eating mites' comment came from.

brewtoo · #11 01-30-2007, 11:32 PM

While I have been very impressed with MB engineering, fit and finish as I've worked through this project, there are a couple of things that have been lacking, IMHO. One of them is the AC condensate drains. The originals are delicate foam with springs inside to support them. You can see the remains of one in the first photo. You can also see the consequences of it leaking onto the floor under the mats. I went to Lowe's plumbing dept and bought some plastic tubing, 3/4"ID and 1"OD. See the second photo. The fit is perfect. Be sure to warm the hose up a bit in hot water and installation is a snap. I am confident that this will not leak. Cost was $1.13 total as opposed to about $11 per side for the original foam hoses.

manny · #12 01-31-2007, 12:45 AM

I can't believe that you're bastardizing such a fine car with " Lowes " parts.

Sure give you a lot of credit for your courage, tackling this project.

#13 03-01-2007, 08:59 AM

As others here, I am NOT a fan of converting to 134. I live in Texas, so all the capacity I can get is needed.

R12 is getting LESS expensive, not MORE! The vehicles that require it are at an age that they are hitting the wrecking yards in record numbers, thus the demand is decreasing. You know, supply and demand determining the prices?

I bought a 30 pound bottle of R12 from Refrigerant Supply in Colorado two years ago for, I think, about $400. At that same time 134 was going up in price. I expect that you could buy a 30 pound bottle now for less than $400. Check it out.

You will need a 609 license, but you can take an online, open book test for $15 in less than a couple of hours.

Good luck,

E150GT · #14 03-01-2007, 09:37 AM

A mechanic said to me that when r134a first came out it was less efficient in original r12 cars. He had wanted to convert my 420sel but I respectfully refused. I told him that I wanted a/c that was cold not cool. He told me that the r134a that is made now is more efficient in cooling and that he could make a conversion now that would be just or almost as cold as r12. He said that maybe two years ago the coversion would leave customers unhappy.

#15 03-01-2007, 09:58 AM

E150GT,

I respectfully suggest that your mechanic is FULL OF IT! Saying that 134 has changed is like saying that the law of gravity has changed such that water will now pour up hill.

I expect that if you took him up on it, he would put one of the junk coolants in the system behind your back and tell you that it is 134. Find a new mechanic.