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Eric Pratt 06-05-2007 11:58 PM

1995 s500 (w140) Climate control
I am getting the following error codes:
E006 E074 E075 E082 E083 E086 E087 E102 E103 E106 E107

I sent the climate control unit to Programma Inc, the charged $399, said the unit had Bad Memory in the code and needed to be cleared and reset.
In addition there were lamps that needed replacement. They said that the unit tested good after their repair.

Today I got it back, hooked it up and I still get the same exact error codes.

I also checked the voltage going to the connector that plugs into the switchover valve block Y11

with Negative to brown terminal I got
Grey/Red terminal 0.56 volts
Blue/Yellow terminal 2.57 to 2.98 volts
Blue/Green terminal 2.11 to 2.50 volts

Are these normal values?

I love this car but it is quickly turning into a money pit.

Anyone have any idea what to do next???

mbdoc 06-06-2007 09:20 AM

What exactly is the a/c system doing or not doing?

Eric Pratt 06-06-2007 10:14 PM

Climate control problems
No blower (already replaced regulator and confirmed that motor is in working condition)

Can hear a/c compressor turn on, but no cold air in the cabin

Heat comes through side vents and defrost when driving down the road.

Auxillary fans used to come on, but do not anymore

Eric Pratt 06-06-2007 11:14 PM

1995 S500 w140 blower not working
Have tried everything, looked at all the posts.
Motor works when grounded.
Put on a new regulator, still doesnt work

Sent climate control unit to programma, paid $399, got back and still have the original DTC error codes:

E006 E074 E075 E082 E083 E086 E087 E102 E103 E106 E107.

I am at my wits end!

vin # WDBGA51E3SA219730
car made in Stutgard 8/94

I hope someone here can help!

mbdoc 06-07-2007 08:59 AM

There are 4 wires at the blower regulator.
Start testing there for command voltages.

Big red wire is power(12V) from the battery (not fused)
Big black wire is ground.
One of the smaller wires should have 12V with the key & a/c controller on.
The last small wire can have from 1V to 7V dependand on the blower knob position.

If you have those voltage readings & the blower is INOP...the regulator IS the problem.

Eric Pratt 06-11-2007 01:31 AM

Climate control issues
After many hours of testing ground and voltage, I finally found the problem.
The auxillary coolant pump control relay module (K30) was bad.

This one relay feeds :

Heater supply unit

Switchover valve block, which in turn feeds a/c blower motor, charcoal filter, and blower motor regulator.

and Warm/cool air switch

As soon as I switched the relay everything worked!

What was affected?
Left and Right Auxillary Fans
Blower Motor
Warm/Cool Air Switch
Charcoal Filter
Right duo valve
Left duo valve
Circulation pump
Auxillary coolant pump

I have been seeking a solution to this problem for months to no avail.
Mercedes mechanics
Shop forum
No one had any idea that the solution was something as simple as a relay.

I suggest to anyone with similiar climate control issues to check the k30 relay, it is under the fuse box that is under the hood.

It could save you lots of $.

I replaced a perfectly good blower motor regulator and sent my cc unit to Programma to test and "fix" for $399.00. All that they did was replace some light bulbs. They did not fix anything.

I hope this post is helpful to someone in the future.

W140 Climate control -> K30 relay.

pcmaher 06-11-2007 09:20 AM

Good info, and good detective work! Thanks for sharing.

Pili380SL 05-18-2010 01:29 PM

I revived this old thread to underline the importance of posting the resolving of a problem, to aid others that might have the same problem in the future. The blower motor on my 95 S coupe stopped working this weekend and thanks to this thread, I quickly located the relay. As luck would have it, the part#, A 001 542 99 19, is the same as the horn relay right next to it, so a quick swap verified that the problem was the relay.

1995s420 11-22-2012 10:33 AM

Thanks Dude!! Saved me the trouble of buying another regulator!!! Only thing I would add is that its location is behind the fuse box(closer to firewall). The large rectangular relay(wiper control module) does have to be removed. Plastic cover then slides back. Did exactly what was posted above(swapped identical blue relays). Bingo!!! Can't thank you enough and all the knowledgeable people on this forum.

big dog 2 11-22-2012 11:23 AM

Went through 2 CCU's rebuilt by Programma for about the same price. Both failed after a short period. Lucky to get refunds from the third party seller. Had better luck pulling a used one from a 1992 300E from a local Pic and Pull for $30. Picked up a spare one too that works perfectly. Second yard only charged me $19 and change.

thomas1966 06-18-2013 04:37 PM

I have same issue and have been looking for the the K30 location for 2 weeks. When you say behind the fuse box? Do I have to remove a cover to see them. Referencing to a 1996 S500 sedan.

gsxr 07-25-2013 07:27 PM


Originally Posted by thomas1966 (Post 3162587)
I have same issue and have been looking for the the K30 location for 2 weeks. When you say behind the fuse box? Do I have to remove a cover to see them. Referencing to a 1996 S500 sedan.

Yep, remove the cover to see the relays. Is your fan totally dead? Could also be the regulator...


waderamsey 10-07-2019 04:18 PM

Early '95 W140, S420, climate control unit not seeing Y11 switchblock, e.g. Error code: EO 06. Typical symptoms, air only thru side and defrost vents. Have tested relay and swapped it, have replaced vacuum manifold in footwell (it was leaking), and have tested blower resister, and blower works perfectly. I used a mityvac and tested the actuators on the y11 block, resulting in center vents opening and blow air etc...
According to MB docs error code EO 06 is a wiring issue. In testing the connector to the Y11 block I get the following readings:

brn = ground

gry/red = 12.22 to 12.03 volts - depending on blower speed

gry/grn (some have it as blu/grn) = 1.9 to 2.3 volt - fluctuates constantly with system on

gry/yel (some have it as blu/yel) = 1.6 to 2.6 - moves fluctuates constantly with system on

Does anyone know what the voltage output should be on the Y11 connector? No matter what flap setting or blower speed I use, same voltage as mentioned above.

The control unit will run through all diagnostics and the flap test, of course nothing happens with the flap test.

Trying to discern if the climate control unit, older style push button, (140 830 2085) is bad or if the Y11 switchblock (140 800 0178) is bad?

Any input is greatly appreciated.

ekipe 10-17-2019 11:46 PM

Sorry for resurrecting this thread too. But after searching the whole intrenet, this is the one closest to my issue.

I have the exactly same problems with my HVAC, but switching the K30 didn't have any effect. I even tested it outside of the car and it is clicking ok, but I have no blower, no current arriving at the heater valves and recirculation pump plugs, no leds lit on the center vent buttons.

Tested for fault codes and got E075; 83; 87; E1 03; 07; 10; 11.

I understand that for the K30 to click, the HVAC module should give it an earth signal, maybe my module is bad? Is there any way to test it?

waderamsey 11-24-2019 10:16 PM

Did you check your voltages?

I solved my problem; the console climate control unit was bad. The big voltage swings, e.g. 1.0 + volt swing confirmed it on gry/grn and gry/yel. I've not seen that anywhere on the internet. I bought a used ccu off ebay, tested the voltage, is swings .02 to .03 volts total. All vents are working correctly for the first time in years and I don't loose vacuum under hard acceleration, bad vacuum manifold passenger side footwell.

Have you tried clearing your error codes on the ccu?
How you tested the voltage at Y11 block and at the blower relay?

Do you have a wiring diagram? There's an eastern european site that has them. I wasn't exactly the one for my car, but it was damned close. That's what helped me a great deal, I was finally able to test voltage up and down the line and reasonably understand how the system worked.

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