123 evaporator cleaning - PeachParts Mercedes-Benz Forum

shadetreemechan · #1 06-09-2020, 08:32 AM

I found several threads about this and figured it might be worth adding my $.02 worth of info.
My 85 wagon has always had anemic ac. Blower is constantly on high but there seemed to be little air coming from vents.

Some of that is due to ac bleeding into the defrost and floor duct circuits even thought the vac pods are good. If anyone knows where the foam in the system needs to be replaced to fix that I am all ears.

Anyway I knew my evaporator was dirty, but wasn't sure how to see it or fix it. My 7 year old son suggested shoving my iphone into the dash and that worked great. Here are the before shots.https://photos.app.goo.gl/Ba1fTsKdTSKai7K36
I purchased a coil cleaning kit online that had a long nozzle for inserting up the evaporator drain tube:https://photos.app.goo.gl/z7jJW1QuRBwDEBLNA
Figuring I would have better luck getting closer to it, I went in via the blower motor and tried to get the product aimed directly at the coil. Here are pics of the foam carrying the debris away and an after pic:https://photos.app.goo.gl/mssbUhuL1hXBRQMn7
As you can see it worked well where I got good contact, but it was not uniformly clean. The directions said it would continue to clean and self rinse if you ran ac for 15 minutes on low blower. I ended up driving to lowes and back which for me takes about an hour. Little change after an hour:https://photos.app.goo.gl/9EiZyR2SyTpN3SsC9
While at Lowes I picked up a can of their coil cleaner intended for residential systems. It was only $6 and instead of 6 oz of product the can had 19 oz of product in it. It did not have a long nozzle to get into the evaporator like the kit I had purchased online, but the nozzle from the online kit fit the lowes can.
Suddenly I had a lot more product to work with. Using that and stopping to take photos along the way I was able to direct the nozzle to the dirty areas.

https://photos.app.goo.gl/HZH19JZoFrXPc8Q37
That can finally ran out, and I didn't want to go to lowes again so I asked the 7 year old again what to do for low volume water spray and he suggested garden sprayer.

We took a pump up garden sprayer filled with water and bent the tip so we could spray right on the evaporator. Within a couple of tries it looked like this:
https://photos.app.goo.gl/Aro9JQWP7xaqVpjt7
Its not perfect, but a huge improvement. I am keeping the nozzle and am buying another couple of cans of the lowes coil cleaner to take on my 84 next.

We went on a 4 hour drive last night in the 85 and you can really tell a difference in the volume of air coming out of the vents, and before as soon as the ac was turned off the windshield fogged from the moisture soaked in the debris on the evaporator. Now that doesn't happen any more.

To me it is a dramatic improvement with relatively little effort. The frequent iphone photos and the long nozzle of the drain tube evaporator kit are the keys to success.

JHZR2 · #2 06-10-2020, 12:01 AM

Thanks for this. Using the iPhone cameras is great for all kinds of stuff. I was trying to clean my upper gutters from my lower roof, and couldn’t get clogs cleared. iPhone to the rescue.

When I pulled the blower the other day, I was expecting to see some portion of the evaporator. No such luck. Seems you have to get around a baffle and a corner. Not easy...

shadetreemechan · #3 06-10-2020, 08:02 AM

Using the phone you can see it. With blower out lay phone on its side and slide it into the cavity. There is a point where you can see the screen while it is pointed at the evaporator. I used that to know when to take pictures. I was very surprised that the phone didn't have to disappear into the evaporator box. You can rotate it right on the edge where its still pretty easy to push the photo button.

Shern · #4 06-11-2020, 11:54 PM

This is awesome.

Cleaning that thing was buried somewhere in my list of things I want to do never.
This technique makes it seem pretty painless.

vwnate1 · #5 06-12-2020, 11:40 AM

Thank you for this ! .

I used I forget what to clean the evaporator in one of my W123's a while back, I too removed the blower motor for access , it's plenty .

I wasn't sure about how clean I was getting it so I bought a Harbor Freight flexible wand camera for $50 ~ it worked fine .

I was surprised as how much dusty crud came out the evaporator drain tube over the transmission ~ I'd been getting wet carpets and thought the foam drain tube was rotted away but it wasn't .