190D tach and a/c suddenly disappeard - PeachParts Mercedes-Benz Forum

yellowbenz · #1 07-02-2006, 05:17 PM

Hello,

Recently solved my a/c problem by jumpering a failed copper line in the pc board of my Climate control unit. Was feeling pretty good about things and then recently the a/c went haywire. A/c only works in defrost setting. In fact nothing else works with regard to the climate control buttons in any other setting (a/c or ec). Also, the tachometer won't work if those other buttons are selected. In addition, the fan will only work if the defrost button is selected. It seems to me that in my search before that there is a connection between the tach and the ccu (overvoltage protection relay?). Anyway, i've about decided to replace the ccu with a reman unit (gdl lab?). My question is, do you think that will solve the problem or is more troubleshooting indicated. I've been reviewing things on mbbraingears but not getting anywhere.

thanks
Kevin
1979 240D
1984 190D manual

JimmyL · #2 07-02-2006, 07:05 PM

I would start trying to find a cheap used CCU. Sounds like the classic symptom, and that doesn't even take into account tracing repair......

Jeremy5848 · #3 07-02-2006, 07:19 PM

Seems to me that there is a sensor that detects whether the compressor is actually turning (instead of being frozen). If the compressor is frozen, the lack of a signal from the sensor tells the ACC not to engage the clutch since this would fry the belt, which also runs something else important (the water pump? I forget). This same sensor is used to run the tach. It thus sounds like there is a problem with this sensor or its wiring or the ACC circuits that handle it.

I'm not sure why it would work in Defrost mode, but that mode does do some things that no other mode does. This is, specifically, put the fan on high speed and go to full-on heat by turning off power to the mono valve, which then opens fully. There is probably a problem in your ACC board that creates this combination of symptoms. It appears that there is an almost infinite combination of problems that the ACC can cause, no two are alike. Everyone who posts here seems to have a slightly different problem. You should probably try resoldering the entire ACC board and all connections to it. If that doesn't work then replace that unit.

Jeremy

yellowbenz · #4 07-02-2006, 08:03 PM

I found a used ccu that looks like mine from a 190E but I'm not sure of the year. Do you think there was much variability in these units?

thanks

Kevin

klaus kallas · #5 07-06-2006, 11:43 AM

Kevin,
This is not related to your thread (although a 190E unit will work, I have one in my 190D).

I just saw a pic of your car in another post and was wondering if you bought it in eastern North Carolina. Looked an awful lot like one I test drove a few months back when it was on ebay. Advertised as a low mile car but had a replaced odometer, non-working a/c, and new paint (appeared to have been wrecked in rear as trunk did not like to shut).

yellowbenz · #6 07-06-2006, 05:24 PM

Yes, I am the sucker that bought that car. I've been totally taken. Had the a/c charged and hardwired a switch for the compressor but i think a new ccu will solve the a/c problem. I thought they might have replaced the speedometer. Only 13000 miles in 3 years seemed unlikely. It is a strong running car though. I'm debating fixing the seats and the other 'little problems' because all in all its a neat little commuter car. I bought it to spare some wear and tear on my 240D. At 260000miles it's still in better shape compared to this 190D. If you have any other impressions about the car I'd appreciate hearing them. I tried to leave some well deserved feedback on the car with e-bay but it took me so long to get the car from those guys that the time expired. I'm probably going to file a complaint with ebay and squareD or whatever that supposed buyer protection program they have. Buy the way, do your 190's have as much lifter noise as this car? I've switched to synthetic and it seems to have helped a little.

Thanks for responding to my post.

Kevin
1979 240D manual
1984 190D manual

klaus kallas · #7 07-06-2006, 10:30 PM

Kevin,

I wouldn't say you are a sucker for buying the car. It looked fine in the pics and they had decent feedback. I sympathize with you having gotten a bit shafted in the deal, however.

The car was not too far from me and sounded good so I went to test drive it. The things I remember include:

The speedometer was definetly replaced.
It had new paint (had body filler in the passenger rear quarter).
Interior was pretty nice, but the climate control and radio console had been apart.
Shifted smooth and drove quite nice (had a new brake booster and stopped on a dime!).
A/C was not working then although the conversion was only a few days old.
Cruise control actuator was disconnected.

Also, it made a hell of a racket when cold. It definetly needs cam followers (lifters). They run about $19 each (8 total). Not to hard to install, but you do need a few special tools (valve spring compressor, etc.). My highest milage 190 (392,000) has never been opened up short of 1 set of lifters and valve stem seals at about 230,000. It is about due again, but still runs great. I run Castrol 15W40 and the previous owner did as well (I've owned for 80,000 miles).

All in all, it actually is a good looking car that just needs some TLC. If I had to guess, given the interior condition and the slight engine needs it probably has about 250,000 on it. The lifters generally last for about 200,000 so that is part of my basis. Trust me, you will grow to love not having to adjust valves every 15,000 (as on the 240D)!!

Again, don't worry. I know you didn't get the car as advertised, but you did get one of the better ones left as these things tend to put on the miles!

Klaus

yellowbenz · #8 07-06-2006, 11:05 PM

Thanks Klaus. This car despite the issues has a hold over me. I like the lines and it is truly economical from a fuel efficiency stand point. It's my daily driver, sparing the 240D. If I ever find another one that I like I'll buy it.
I'm going to try the lifters myself after I get the clutch master cylinder bled on the 240D.

Kevin

1979 240D manual
1984 190D manual

D VanWalleghen · #9 08-04-2006, 07:14 PM

Hello everyone,
I to have a 190D with an intermittant dead tach and no function from the compressor ( fully charged ). My tach does work once in a while. When working the engine idles noticably smoother. If I try to turn on the AC when the tach is working it immediatly drops to zero. It sounds like I need to start shopping for a climate control module. Does anyone have any other thoughts?
Thanks Don

yellowbenz · #10 08-04-2006, 07:40 PM

What year is your car? 1984 is different from later models. Check your fuses. I believe it's number 8 that was melted on my car (at work will check later). Ultimately, to cure all of my woes I had to get a new (used) CCU.

Kevin
1979 240D manual
1984 190D manual

D VanWalleghen · #11 08-04-2006, 08:13 PM

I have a 1985. sorry I didn't mention it I was just excited to talk to someone with my problem!

pdrayton · #12 08-04-2006, 08:35 PM

I have a 300D 2.5, 124 chassis - anyway, had the same sort of issues and it turned out to be a overvoltage protection fuse. This fuse, and a few others like it, are not in the fuse box. Look behind and around the battery (front passenger side on a 124). Also, get behind the battery, between the battery and the firewall (at least on a 124) - there are some fuses there.

Might help. Might not.

Also, using mobil1 synthetic fixed the cam follower issues on this car. Try that first before replacing, you might be surprised. Takes a few hundred/thousand miles though. I am totally sold - I only use Mobil1 from now on.

yellowbenz · #13 08-04-2006, 10:01 PM

The fuse number 1 melted and took out my tach and a/c previously. Yes, 1985 and up has the OVP. Might try pulling and reinserting the Klima relay also back behind the battery (big relay shaped like a cigarette pack). mb.braingears.com has the full troubleshooting guide for the hvac and I'd highly recommend checking it out.

Re: noisy lifters. I've got the new Mobil1 turbo diesel in the trunk ready to change this weekend hopefully.

Good luck

Kevin
1979 240D manual
1984 190D manual