AC Evaporator - PeachParts Mercedes-Benz Forum

Tom McMenamin · #1 07-13-2015, 07:19 PM

It appears that replacement of the Evaporator is not an expensive part but a monster job on the labor side Some sites indicate 16 hours and that no short cuts are available.

I am an old guy with a 1988 560Sl and apparently I need an evaporator. I am desperate to find out if Their is any alternative to this replacement? Is it simply to sweat without it or is there a way to make it better?

I really need help on this as I absolutely can't afford the labor to replace it!

Phillytwotank · #2 07-13-2015, 07:33 PM

Depending on how bad it is leaking... There are some super duty leak stop products out there that may do the trick.

Tom McMenamin · #3 07-13-2015, 07:47 PM

It is not leaking. AC is not cooling? I am told that it is an evaporator problem?????

97 SL320 · #4 07-13-2015, 07:53 PM

Have a look on U tube, someone may have documented the process or at least dash removal.

I may need to do an evap on Moms 97 C280 at some point. I've been in and around the car business for 40 years and have developed some tricks.

Any time I take a large assembly apart, I lay parts behind the car in the order that they come off and on the side they should go back onto. I also intertwine parts that must go on together. putting screws back from where they came is a trick to keep things straight as is making an approximate cardboard template of where screws should go.

Take pictures , notes in order.

Cars are generally made to be rapidly assembled, for removal, try to mimic what they had done. Take big chunks out of the car and not lots of small parts. If the bolts are impossible to take out, something else needs to come off. ( There are times when only one difficult bolt is holding the last piece on so use judgement. )

I think the expansion valve on this car is hidden under the dash, now would be a good time to change it.

PARSHOOT1 · #5 07-13-2015, 07:54 PM

Your problem was diagnosed at a dealer service dept?

97 SL320 · #6 07-13-2015, 07:56 PM

Just saw you post 3. The evaporator isn't the problem if it isn't leaking.

You may have an expansion valve problem. Putting a set of AC gauges on it will determine that. Very low or vacuum on the low side , very high pressure on the high side. Maybe a bit of cooling at first start up but no cooling after a minute or two.

Phillytwotank · #7 07-13-2015, 08:02 PM

The only problem that the evaporator could have that would cause no cooling would be a leak. Alowing the refrigerant to leak out and causing the system to stop working.

Or

It's possible that it could be filthy dirty to the point where it would deminish cooling. That would be a much easier fix. I'm not at all familiar with the r107 chassis but I would imagine that an in car evaporator cleaning would be possible.

Tom McMenamin · #8 07-13-2015, 09:26 PM

As usual, I am as guilty as all others when I don't explain my technical problem as completely as I should. How can you solicit the correct answer if you don't ask the question properly.

I have a 1988 560 SL and ahave been on this site for a long time. I considered Phil one of my best friends.

My car has had an on and off air cond problem for the last two years. The AC or heart would not come on properly due to a faulty ignition switch. If I touched the key ever so slightky the AC or heat would come on and the fan would power quite strong. As time went on this Spring once in a while after tweeking the key NOTHING would hsppen. Or it would come on after a few minutes of operation. It would at times not work at all but the next drive it would come on and work. Soetimes the AC would be slow to gather itself and blow hot air. the next drive it would slowly build up and blow like crazy!!!

I have had no leaks from under the dash. The tubes on either side of the car connected to the dash have been blown out. I am not sure if the Fan on the front of the car which blows across the condenser works.

The car is in the body shop right now having any and all rust rremoved and over the last few weeks I have moved to Florida. Air Conditioning is imperative here. I am told the Evaporator is my problem, but I have had no leaks to the best of my knowledge. Does it make sense to take the car to an AC Expert and get a complete overview of the sytem and get a consensus befor moving ahead. Would it make more sense to take it to the Mercedes Dealer and get a consensus on the AC and then attempt to find a more reasonable repair shop? Or maybe the repair is reasonable and a qualified Mercedes Benz person could define and repair?

What is the advice of this Board? Are there any suggestions from any of you as to what you feel might be my problem? All input is welcome

Thanks to Phillytwotank, 97SL320, and Parshoot1. It could very well be the Expansion Valve or a Dirty Evaporator. Whats the process on cleaning it? Is there a DIYon here or somewhere else that anyone knows of. The U tube Cleaning of the Evaporator is not very good or I am dumb. Could be 50/50 of each!

Thanks in advance and god Bless all of you for trying to help

Tom McMenamin · #9 07-13-2015, 09:44 PM

As I said I have moved to Orange Park Florida!! Does anyone know an excellent shade tree Mercedes mechanic that they trust? How about an AC shop for my 560? Does anyone have a trusted AC Shop or Mercedes Dealer or mechanic???

As stated the car is in the Body Shop in Ft Lauderdale right now and anyone in that \City or Miami that you feel qualified please pass it on.

timm9 · #10 07-14-2015, 06:40 PM

Please excuse my uninvited interruption in your thread...

I also was told (by two different shops) that the Evaporator on my 82 SL was shot and needed to be replaced. I was also quoted 26 hours of labor to get to it and was getting ready to order parts for the job when a good friend asked me if I had actually looked 'long and hard' for the leak to confirm it was the Evaporator which I had not.

Long story short it turned out to be the Condenser and not the Evaporator which is a much easier fix thank God.

Tim

97 SL320 · #11 07-14-2015, 07:23 PM

Timm9, no interruption, adding data points is always helpful.

One way to isolate leaks is to lightly charge ( gas only with engine off ) or use nitrogen to fill the system then pinch off hoses if they are in good condition. If you fill with liquid freon it will take a long time for the pressure to drop as the liquid boils off so don't do that.

It goes like this:

Pressurize the system, see that it is leaking down, try to locate with ultrasonic and sniffer leak detector . ( hint, with a gas only charge in my 97 C280,it took overnight to loose 30 or so PSI. )

Pinch off hoses to isolate the evaporator, compressor , condenser. Found that the condenser would lose pressure when in the system. Pull the aux fans, find corroded through spot. Sniffer would not trigger due to corroded area being inaccessible, replaced condenser.

Move a year on, needed to replace expansion valve as a precaution. ( I had all of the plastic out of the way during a windshield replacement anyway giving full access to the valve )

Was only able to pump out about 450 Gram from a 850 system. Did the gas only charge, found it took a week to drop 5 PSI ,( 40 to 35 ) this equals 400 G / ~ 0.9 Lb per year. Tried to find leak, one time got a short sniffer blip from the AC vents. Might be evaporator leak not sure. The compressor and 2 hoses are year old. Recharged system, will be OK for now.

There is a time lapse evaporator core replacement on a C class W 202 ( 95 to 00 C 220 / C 230 / C 280 ) that will give some idea what is involved.