Greets, the CCU stopped working recently- the #7 fuse has power and is good- I can hear a clicking when I put it in with key on coming from pass side- the OVP relay is new but is there another relay?

The CCU has light going to it- but the buttons do nothing, no flaps activated, etc. Like its dead. The motor in this car was replaced back in Jan so perhaps a connection was left off?

I have 2 CCU units and swapped the other in with no difference, which leads me to believe its a relay.

thanks, my wife is driving around in a heat wave with no AC.

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1995 E300 diesel

Hello - I'm attaching a couple of DIY tech articles that I hope will help you troubleshoot and resolve the climate control issue to get your wife comfortable in the car Please let us know if you have any questions!

Mercedes-Benz W124 Climate Controls Removal | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article

Mercedes-Benz W124 Blower Motor Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article

Thank you Dmitry, I am familiar with both processes as I have removed the blower motor from a donor car to have a spare. My question is in troubleshooting and locating the relay. I just put a new OVP relay in it a few months ago with the motor swap. When I had it in shop a few weeks ago to charge the freon up the compressor would not come on.

thx!

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1995 E300 diesel

No problem at all; if you're unable to find an answer here through our members, feel free to give us a call at 888-280-7799 and one of our MB part specialists may be able to help you out. Best of luck!

Isn't it true that the compressor will not come on if you do not have enough freon? Could your Freon be low?

Sorry for delay. Its not just the compressor, no vent or heat, I can't hear any movement of vacuum vents. Or should I say barely a vent when moving at highway speeds. I am suspecting the relay but I have no idea which one it is! I do have spares from donor car.

Or it could be vacuum related, not sure.

thanks!

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1995 E300 diesel

Have you tried disconnecting the auxillary water pump. Sometimes these draw more than 2 amps as they age which in turn causes a failure of the Ccu as that circuit is unprotected. This happened to me but the fan would operate in high only.

Have you pulled your fan and speed controller to test for operation?

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Where is the aux water pump? I have not pulled the fan motor yet, although I have a spare from a donor car and I know what a PITA it is to get at.

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1995 E300 diesel

Look at the male connector pins of the right side of the CCU. Notice any build up? Just a slight lack of connectivity here will make things go crazy. Take a brass wire brush or equivalent and get those pins shinny. Its not uncommon to see a black build up around this area and you should be suspect if you see this.

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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

Mine is tucked under the windshield washer bottle you should be able to see part of it with the bottle installed, easy to get at with the bottle removed but my car is a 92.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Thanks for the replies- will check out tonight!

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1995 E300 diesel

Long shot, but there is a vacuum hose manifold behind the airbag which should have been a glove box. I had one hose come loose from there once. Worth checking.

Rgds,
Chris W.
ex '95 E300D, 467K

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Objects in closer are mirror than they appear.

I disconnected the aux water pump- no difference.

Pins to CCU are shiny clean.

No loose/disconnected vacuum lines I can see.

I can hear a faint vacuum valve moving switching between off and economy and also defrost. No change in engine when putting AC on.

Is it possible to test the fan without removing the wiper/apparatus?

Frustrating this car is.

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1995 E300 diesel

Man I feel for you. Every time one of the ones the lovely Ms engatwork drives hick ups she starts talking about how nice it would be to drive a car that was built within the past decade. Her DD is a '98 E300, best car ever built.

PM me an email and I'll send wiring diagram.

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Jim

Fixed it today, regulator was bad. I put the spare I had in, don't forget the heat sink paste!

Now I have to diagnose the issue with the wiper after I put it back together and it stopped working when I stopped at the car wash- was working fine when I reinstalled it.....

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1995 E300 diesel