Evaporator clean in situ - 123 240D - PeachParts Mercedes-Benz Forum

pdrayton · #1 07-08-2006, 01:03 PM

My a/c is not blowing as cold as it could considering it has a new compressor dryer and valve, and R12.

So, the 23 odd year old evaporator might have a little dirt on it. I've seen the pictures of others, and think mine is probably the same.

I'm not up for the evaporator removal process. Another guy cleaned his evap on a 124 without removing it, but he hasn't replied to my questions about how to get the box off it while you're looking at it from the drivers side under the steering wheel.

I've searched the forum, but can't find any info on it. Someone did mention they were able to clean it a bit, but I can't find that post.

So, do you know how to clean the evap in a 123 without removing it and half the car?

I can see the black plastic case that holds it and the blower motor from the driver's side after removing the lower kick panel. The box has clips on and I'm wondering if I can take some of them off and get at the evap with a hose and some degreaser? Or, will I just make it so I can't get the box back on and have to remove half the car to put it back together?

Or is there some other clever trick? Like squirting water and degreaser up the drip tube?

It would be really cool (pun intended, I'm so funny) to get the a/c working better without spending three days on it.

Thanks.

jbaj007 · #2 07-08-2006, 04:59 PM

FWIW on a 126

126 evaporator cleaned (and minty fresh ;))

dmorrison · #3 07-08-2006, 06:44 PM

Ive been looking at all the pictures I have on both evaporator removals and am trying to figure IF you can get to the evaporator without removing the box. Jbaj007's post is the technique I figured below.

Go to this post to reference the picture I will discuss.

http://www.peachparts.com/Wikka/W123Evaporator

Go to picture #127, #128 and #129

#127 is the center of the car evaporator area. #128 is the passenger side, notice the round fan opening. #129 is the same area from above.

These pictures are actually from the bottom of the evaporator box looking up. The bottom of the picture is the front of the car. also in these pictures the bottom of the evap case has been removed. That round hole is actually were the top of the blower squirrel cage would be. Look at picture #123 to see the top of the squirrel cage. You can also use the expansion valve to orient yourself.

Find a 1/2 to 3/4 round baby bottle washer type brush. Remove the blower motor. Install a shopvac hose in the center vent and close or tape over all the other vents if possible. slide the brush in through the fan opening to wards the front ( front of car orientation) of the evap box. ( make note of the air vanes in the box in picture #129) brush downward and hopefully this will remove some debris. I have not tried this, Just looked at all my pictures.

****Considering the other side of the evaporator, there is no way to get to this without unclipping sections of the evap box. Trying to remove the lower section while it is in the car would be a nightmare. And you would not be able to remove the section just drop it 1/2-1 inch. Probably not worth the effort for the results. And I don't think you could reinstall, or even remove, the front clips on the box. It would be easier to remove everything then trying to rig it this way.

So you might be able to clean one side of the evaporator,, Give it a try if you feel adventurous.

Dave

Second thoughts on this. If you feel adventurous. a small 1/4 inch diameter copper tube with a pin hole outlet for water, A spray type nozzle effect. Make sure your vent drains are in very good shape. ther are 2 in the W123. one at teh bottom and the other goes thru the firewall next to the Ac hoses.
Using the copper tube attached to a garden how you MIGHT be able to spray a fine stream into the evaporator and allow it to drain out the drain. Cleaning foam and this technique might help. It would be a good amount of water, but the system is designed to handle water and should not be a problem. Consider removing the ETR sensor first. Be very careful not to force the copper tube into the evap and damage it. Besides the ETR nothing else is in there that could be ruined except some evap vanes. So just be careful.

Dave

pdrayton · #4 07-08-2006, 07:51 PM

Thanks Chaps.

I'll give it a go through the blower hole.

I have a thermometer in the vents and have been monitoring the temps for about a week, so I'll know how effective it is and will post any info I get.

Paul

redassag00 · #5 08-03-2006, 10:21 AM

did you have any luck with this?

pdrayton · #6 08-03-2006, 11:01 AM

I was thinking about doing this post yesterday, what a lazy b'tard - I didn't.

Anyway, thanks for the bump - here's theupdate.

Getting to the evap from the blower motor hole is pretty easy and quick - drop the blower motor (about 4 screws and it comes rightout) and you can feel all along one side of the evap.

My evap was clean for about the first 2/3rds and then pretty caked up. I sprayed purple power on it with a small home hand pumped pressure sprayer (from LOWEs, or walmart - quite cheap and effective). Some gunk came off for sure.

I also got some proper a/c cleaner in a spray bottle from LOWE's and used it on my home a/c before spraying it on the car evap. Not sure if it did anything or not since you can't really see in the evap box.

So I think I cleaned it somewhat (using the wife's compact mirror and a flashlight) to see into the box. However, there is no appreciable performance increase that I can detect. My thermometer still shows a drop of about 30 F when running the ac. I have checked the Merc specs on this car's ac and it is about right so I am thinking it just has crappy a/c and that's all. Basically when it is 95F outside, I can keep cool inside with full a/c. So it works for me, but not great.

I'd be interested to hear if anyone has better performance. with this system. I have a new R4 compressor, expansion valve (say R134 on it, and I have R12 in the system - does that matter?) etc. Perhaps I put too much mineral oil in and that is efffecting the performance? I don't know. Any ideas?

Back to the plot of the post though - getting to the evap to clean it is fairly easy and worth a go if you think it may be clogged up.

Cr from Texas · #7 08-12-2009, 08:08 PM

Thanks for the bump. I think I'll try this stuff by dropping the blower assembly.
http://www.autoacsystems.com/_store/storeopen_odor.html
Based on reading this thread, could I spray through the driver foot vent and also get to the evaporator? Is there an ideal place to drill a cleaning hole for access? If you vacuum first as suggested in an old post by connecting a shop vac to the center vent, wouldn't that be trying to pull the crud through the evaporator? Wouldn't it be better to put the shop vac in the channel going from the blower to the evaporator and try to suck it out in reverse flow?