I have been experiencing and living with climate control issues for years in my 190 D 2.5 Turbo.

I have multiple CCU "head units", all of which display some type of peculiarity. (only scorching hot, only freezing cold, improper vent controls, etc).

I'm in the mood to make this system work the way it was designed. I'm not afraid of pulling the dash if needed, or repairing/replacing whatever components need to be fixed.

I figured that I had better start with a head unit that works properly, before moving onto the electrical/vacuum solenoid manifold and the flap acutators.

Anyway, I took the bottom cover off one of the CCU units today, and inspected the solder joints under a stereo microscope. I found one connection that was clearly cracked, so I resoldered it.

It seems to me, that at one time, I saw an online tutorial showing the common connections which go bad on these units, but I can't find it now.

I also thought there was a guy who would essentially rebuild the head units for customers who sent their units to him. I can't find any of these resources now.

Can anyone help with a link to a tutorial specifically geared towards the "head unit" rebuild, or contact information to the guy who was rebuilding these things?

Steve.

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'93 190E/D 2.5 Turbodiesel 5-speed (daily driver)
'87 190D 2.5 Turbo rustbucket - parts car
'84 Dodge Rampage diesel - Land Speed Record Holder
'13 Ram 2500 Diesel
'05 Toyota 4Runner

Forum member jamesdean can resolder it for you BUT I don't believe he has the equipment to bench test it. GDL can actually rebuild the unit for you (although it looks like there's only a limited number that they work on).

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Jetmugg,

I think you may be referring to me. I do offer a climate control unit repair/refresh service that include inspection, re-solder and re-cap of the whole unit. Drop me an email or PM if you are interested.

Here are some photos of an early W201 unit that I did for a fellow member:
http://imgur.com/a/y2osm

My climate control unit service is two-fold. I re-solder the whole unit as well as replace all of the capacitors that go bad on it.

You are correct that I do not have a testing setup for it though. One day I will.

Rebuild is a bit of a vague term, degree can vary from "fix it so that it works" to "fix it so that it lasts" to "replace suspect components" to"replace everything on it."

GDL's prices, at least for the cruise amps are high. Last I saw it was $300-400 or something but then again different services and circumstances drive prices.

I cannot (yet) test so I charge less. I also don't have many mechanical parts although I can get some (new temp wheels from MB, etc).

My primary goal with these services are to help out fellow enthusiasts as over the years you've all helped me so much.

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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Although the head unit could be bad, the common problems are vacuum related. Before you spend a lot of time and money on the electronics, remove the glove box liner. There's a multi-port switchover valve that's tie-wrapped to a support rail just below the glovebox and to the extreme right. This where all the vacuum and electrical signals come together. Check the color coding on the vacuum lines, and unplug the ones going to the vacuum pods one by one. Use a mityvac to be sure that each pod is holding vacuum. Any leaky pod would cause you to blast heat. Dashboard removal is required to replace the pods.

If you have to remove the dash, also be sure to replace the rheostat, as it does wear over years of use.

Here's a photo writeup I did when I pulled my dash:

190 Restoration

I bought a rebuilt unit from ProgRama, but I haven't actually been able to test if it work or if the head unit was even the issue because when I was trying to test it, I noticed a broken wire on one of the connectors so I may not have needed a rebuilt unit anyway (though mine had moisture in it from when the AC condensate drains clogged). Mine was $112.50 plus a $20 core charge.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

This is one of the aids to which you may be referring:

Troubleshooting the Mercedes-Benz 190 Tempmatic ACC Climate Control System


I found my problem to be the feedback potentiometer. I have a number of the CCU's, tried them all and had the same problem. I had already replaced the switchover valve and tested vacuum which was fine, along with all the pods. I bit the bullet, removed the dash and replaced the potentiometer and adjusted it, and my AC has been working exactly as designed for several years now.