Heat Wanted - '84 190D 2.2 - PeachParts Mercedes-Benz Forum

Jetmugg · #1 01-15-2007, 01:15 PM

I appreciate any and all help in getting some heat into the cabin of my '84 190D. I currently have "intermittent" heat, and it's cold outside (and most of the time inside the car). I've used the search function, but still have unanswered questions.

My current issue is as follows: My hot air "comes and goes" while driving. Sometimes I get nice warm air like it's supposed to have, but then 1 minute later, I'm getting nothing but frigid cold air from the outer dash vents, the defroster vents, and/or the footwell vents. Then in another couple of minutes, the air will be hot again.

I've checked the heater shutoff valve in the cowl area, there is hot water on both sides of the valve. The heater core is getting hot, it's just that sometimes the air entering the cabin is not passing over the heater core. My "main air flap" vacuum pod won't hold vacuum - I've ordered a new one, and I am currently driving around with a Mityvac hooked to this pod, pumping it up as I drive (sometimes this seems to help restore the heat).

My understanding is that the "default" failure mode for the climate control system is hot air out of the defrost and outer dash vents. Right now, I would be very happy to have that condition. Any tips on how to make the system operate in default mode would be great. The ice cold air I'm getting out of my defroster vents doesn't help to clear the windshield. If I disconnect the vacuum feed line to the switchover valve, will this put me in "default" mode until I can make the proper repairs?

The indicator lights on the CC unit do not light up either. I have no idea whether these are related issues or not. I understand that these lights are fed by the dash lighting circuit - I will try to check out the connections this evening.

I know that these CC units are complex and often problematic - this is not my first MB Diesel. Right now I'm just looking for some practical advice to get some hot air flowing - possibly some advice from another W201 owner.

Thanks a million.

Steve M.

ytr1903 · #2 01-15-2007, 01:42 PM

Steve,

I may have the answer for you, but it isn't what you want to hear. I was getting the same symptoms out of my daughter's turbo last summer. It ended up being the potentiometer, which is located up under the dash. The part itself is not particularly expensive, but getting to it is a nightmare. The dash must come off. I may be wrong and hope that I am. Somebody else can chime in here if I am wrong. You are right about this being a very complex and problematic system. Good luck.

Tom

diesel friend · #3 01-15-2007, 03:34 PM

Not sure where the problem is but I would change the thermostat before I remove the dash. Changed the dash in my car (86 W201D 2.5) and still remember the work involved. My present and the previous 2.2L D supplied sufficient heat. Feel, the 2.5 warms up a bit faster.

Jetmugg · #4 01-16-2007, 08:23 AM

Brrrrrr - very chilly ride to work this morning. It's about 15 degrees outside, and about 17 degrees inside the car. (I farted and it warmed up a bit).

I took the CC unit out last night, visually checked for burned connections, and found 2 that looked like they might be bad. I resoldered them, put the unit back in, and it seemed to work for about 2 minutes (blowing hot air). Then I could hear the clicking of the switchover valve, and 30 seconds later I was freezing again.

Right now, I think that the entire CC "head unit" is bad, but I'm not ready to throw down the $$ on a reman unit.

Is there a way for me to make the system go into the default "fail" mode where I will only have hot air out the outer dash vents and defroster?

Steve M.

ytr1903 · #5 01-16-2007, 08:31 AM

Steve,

You may want to check this site.

http://cacavas.com/mb/TTM.html

Tom

Jetmugg · #6 01-16-2007, 09:37 AM

Tom:
Thanks for the link. That's exactly the kind of technical information that I was looking for. I guess I need to spend some time with the digital multimeter Do you hvae the climate control systems working in both of your 190's?

Interested in another one yet?

Steve.

ytr1903 · #7 01-16-2007, 10:25 AM

Ha! No more cars (190 or otherwise) for the moment.

I jury-rigged the turbo by bypassing the Klima relay. It is supposed to be a temporary fix, but it seems to have become permanent. I just can't come to grips with letting the moths out of the wallet for a new Klima. The white car has a perfectly operational climate control system for the moment.

Keep us up-to-date on this problem. There isn't that much info here on this screwy Tempmatic system.

Tom

Jetmugg · #8 01-16-2007, 10:36 AM

Right now, I'm just looking for a quick fix as well. Heat would be nice. I have heard about bypassing the Klima relay, but don't know anything more about it. What is involved with bypassing the Klima, and what does it allow you do after it is bypassed?

I'm going to mess around with it some more this evening. Even if I can get it into the default/failure mode, I would be happy for now. I think I might try disconnecting the vacuum supply to the switchover valve to see if that will put it in default mode.

I've already had the guage cluster out, the glove box out, the console out, etc., but I'm definitely not looking forward to pulling the whole dash out. That would be a last resort type of act.

SteveM

yellowbenz · #9 01-16-2007, 11:09 AM

No Klima relay on the 1984 190D.

Kevin

1979 240D manual
1984 190D manual

yellowbenz · #10 01-16-2007, 11:21 AM

I'm an idiot. Yes, there is a Klima. You know there are some brilliant guys on this site, but I think for the 190D you really need to talk to Marshall Booth. He knows these cars inside and out. He mainly posts on the MBCA site. The cd manual for this car is probably a good investment also. Mb braingears is too unpredictable.

Kevin
1979 240D manual
1984 190D manual

ytr1903 · #11 01-16-2007, 11:43 AM

Steve,

Take a look at this thread for a in-depth discussion of the Klima and how to bypass it for A/C operation. Check response #51 in the thread. Brian Carlton helped me immensely in understanding what is going on with the ACC. The thread is about the 126 system but the Klima bypass applies to the 201 too.

That being said, I don't think that the Klima is responsible for your problem right now. Check that potentiometer per the website that I sent to you. If it is not properly opening and closing the door to leave the heat into the cabin, you will have either too much heat or not enough, or even none.

Marshall Booth certainly is a potential resource to probe, but my experience with this problem and the A/C problem was addressed over on this site.

Tom

http://www.peachparts.com/shopforum/showthread.php?t=131216&page=4&highlight=klima

greenlogic · #12 01-16-2007, 11:49 AM

I have a 1984 190d 2.2 also and I am having the same problem. The way I have been getting heat is to get the heat running on defrost mode first. Then once it's blowing heat I can back the temp wheel off full heat to a little short of the 22 degree mark and swith to footwell or any other positions and it seems to work fine after that.

I have no vac leaks in the cc system I have tested with a mityvac and every green line holds vac. So not sure if it is vac related. Probably fried circuitry in the CC.
How is your aux. water pump?

Jetmugg · #13 01-16-2007, 11:56 AM

The aux water pump seems to be working properly. The heater core gets plenty hot, and when the system decides to let me have any warm air, it is also hot. The problem is that I just can't get hot air when I want it, it's intermittent at best. And when it goes cold, it goes absolutely ice cold. Not just lukewarm, but outside-air-temp cold.

I think I've tried every combination of defrost, temp wheel, footwells, dash vents, etc. Sometimes I get hot air, and sometimes I get frigid air. I'm going to check that potentiometer this evening, and will also try to get it into default mode, where I can at least have hot air from the defroster and vents.

SteveM.

babymog · #14 01-16-2007, 08:13 PM

Pulling the 201 dash isn't really that bad IMO.

I pulled one on a '93, pulled the vents, speaker grilles, gauges, steering wheel, center console, and pretty much that was it. I did it with the glovebox in place, think I had around 30minutes into the task.