climate lack-of-control system, 1984 300D - PeachParts Mercedes-Benz Forum

Jerry_W · #1 06-09-2013, 10:11 PM

I have been trying to get some modicum of control from my climate control system.
I have outer dash vents and defrost vent HEAT under all conditions (except off), the fan seems to have a mind of its own, and the heat is being pushed into the car even when the AC compressor is engaged (and there is a temperature differential between the high side and low side hoses). Mitivac shows no leak at the green supply hose, but I can't seem to get the system to open the #1 vacuum solenoid and check for leaks downstream.
The diagram from the CD manual I have (supposed to be the FSM) seems to show vacuum lines being connected to the pushbutton switch unit, so no help there. It does tell me what position everything is supposed to be in when working correctly, but if it was working, I probably would not be in the manual!
FYI, all that is left the foam hose to the dash sensor is a gob of goo.
Where do I go from here?

MTUpower · #2 06-09-2013, 10:14 PM

What year is the car- and what model? Hard to diagnose without that info. The push button controls can go bad in all models- I just went thru that with my 82 300TD and it took three used units to make the compressor and heat work as designed.

Jerry_W · #3 06-09-2013, 11:04 PM

As per signature, 1984 300D.
Is there any decent way to test the control panel, ie a pin diagram where if you are in position (X), there should be continuity on pins 2 and 9, and so forth?
I did swap the pushbutton unit from the parts car in, mostly because the lamp sockets on mine were shot, (sockets melted and broken bulbs stuck in them) but it did not make a difference in function.
The system sort of baffles me. I understand the vacuum system somewhat, but I don't know what actuates the electric parts.
Additional info: the aux waterpump isn't working, but I don't think that would affect the controls.

SD Blue · #4 06-10-2013, 10:00 AM

Sounds like you may have Pushbutton Controller issues or even the possibility of a monovalve problem. For the controller, it is likely to be cracked solder joints. There are 3 boards arranged in an "H" pattern and the solder joints tend to crack where they meet. If you don't feel comfortable doing the solder work yourself, ProgRama Remanufactured Electronic Control Modules 2-3 YEAR warranty will do a repair of your unit for ~$130 or replacement for ~$160.

JamesDean · #5 06-10-2013, 09:11 PM

If you don't feel like paying ProgRama, I can reflow the solder joints for you at a lower price.

Also keep in mind that the SD's use two other modules as part of the climate control system. There is a unit called the 'temperature regulator' that may be damaged or questionable.

The three module are:
push button unit
blower control
temperature regulator and controller.

Blower Controller:
Inside the box: Blower Resistor Relay box

PBU and Temp Regulator:
Inside the box: W126 Automatic Climate Control. First Gen.

Jerry_W · #6 06-10-2013, 10:33 PM

Thanx, JamesDean. I may have to take you up on that. Kinda (rots) that the AC seems to work, but I can't access it!
As I found a Temperatureregler (sp?) way up under the dash on the right side, I am guessing the SD system you took the pictures of is similar to the system I have (a D)?
Just to verify, the most common failure would be bad solder joints / loose components ? If so, I will check one set, and leave one set unmolested to ship your direction if I fail to detect and fix the problem. (I am nowhere near your level of expertise, but I am not completely over my head as far as soldering components. If it is obviously broke, fine. If it is any component much past a resister, I don't have the test gear to check.)
As far as the blower fan speeds, it appears to have several. I have a resistor box on the fenderwell, I thought that was my fan speed control (corrections cheerfully accepted).
2 more questions, and please chime in if I am wrong in my assumptions!
1) I will have to verify whether the aux pump works (currently not operating, but if it isn't getting power from left plug pins 10 and 12, it wouldn't, will try feeding it direct)
2) how critical is the foam pipe to the dash sensor to system operation?

Jerry_W · #7 06-11-2013, 10:55 PM

Update:
Units from parts car:
TEMPERATURREGLER #1 147 328 025
GEBLASEREGLER #1 147 328 026

First item is obvious, second device, fan speed ?, correct, or am I once again off base ?
I had thought the small box on the right inner fender was the fan speed (at least, that is how it was done on a very early Triumph I used to have, as the coiled wire resistors get as hot as a heating element, so I assumed it was a european thing).
Input requested, thanx.

Jerry_W · #8 06-13-2013, 09:33 PM

Shameless bump, looking for some help to see if I am even on right track here.

JamesDean · #9 06-13-2013, 10:25 PM

Quote:

Originally Posted by Jerry_W

Thanx, JamesDean. I may have to take you up on that. Kinda (rots) that the AC seems to work, but I can't access it!
As I found a Temperatureregler (sp?) way up under the dash on the right side, I am guessing the SD system you took the pictures of is similar to the system I have (a D)?
Just to verify, the most common failure would be bad solder joints / loose components ? If so, I will check one set, and leave one set unmolested to ship your direction if I fail to detect and fix the problem. (I am nowhere near your level of expertise, but I am not completely over my head as far as soldering components. If it is obviously broke, fine. If it is any component much past a resister, I don't have the test gear to check.)
As far as the blower fan speeds, it appears to have several. I have a resistor box on the fenderwell, I thought that was my fan speed control (corrections cheerfully accepted).
2 more questions, and please chime in if I am wrong in my assumptions!
1) I will have to verify whether the aux pump works (currently not operating, but if it isn't getting power from left plug pins 10 and 12, it wouldn't, will try feeding it direct)
2) how critical is the foam pipe to the dash sensor to system operation?

Sorry I didnt reply sooner. Im out of town at the moment on business.

The stuff I worked on was from a 300SD. It may have similiarly named items as your 300D. I do believe some of the items are interchangeable.

Yes a common failure would be bad solder joints which can lead to loose or broken components. Another would be aged/bad capacitors. I would be happy to work on whatever you'd like to send my way. Just shoot me and email and we can work out the particulars.

1) It think it seems like a fine test, want to do is see how much current it draws when its running. It should draw less than 1 amp. If it draws more it should be replaced. You should also install a fuse on it to prevent it from killing your push button control unit and/or entier car. I believe someone on here had their car catch fire when the aux pump froze.

2) Im not sure if the foam pipe directs air to a sensor or if the sensor is at the dash and the foam pipe is merely encapsualting the wire..Soo I'm not sure.

JamesDean · #10 06-13-2013, 10:28 PM

Quote:

Originally Posted by Jerry_W

Update:
Units from parts car:
TEMPERATURREGLER #1 147 328 025
GEBLASEREGLER #1 147 328 026

First item is obvious, second device, fan speed ?, correct, or am I once again off base ?
I had thought the small box on the right inner fender was the fan speed (at least, that is how it was done on a very early Triumph I used to have, as the coiled wire resistors get as hot as a heating element, so I assumed it was a european thing).
Input requested, thanx.

The GEBLASERREGLER is the blower speed control box.

Inside the box: Blower Resistor Relay box

Jerry_W · #11 06-14-2013, 11:28 PM

Thanx again.
The inline fuse strikes me as an excellent idea.
I will be testing and diagnosing this weekend.

Mölyapina · #12 06-15-2013, 06:18 AM

I have both cars in the driveway at the moment, and I believe that all three bits are shared between them.

my123ca · #13 06-15-2013, 12:02 PM

Quote:

Originally Posted by Jerry_W

Additional info: the aux waterpump isn't working, but I don't think that would affect the controls.

Pull the connector to the aux. pump for now while you diagnose the issue. The switchover valves are known to break. They should measure 45 ohms. Switchover valve #1 gets power when defrost is pressed.

JamesDean · #14 06-15-2013, 12:06 PM

Quote:

Originally Posted by Jooseppi Luna

I have both cars in the driveway at the moment, and I believe that all three bits are shared between them.

Verify this with part numbers.

I remember looking at this before and I know the push button units are NOT shared. The temp regulator I think IS. Probably the blower too.

Jerry_W · #15 07-04-2013, 10:23 PM

Reference image.

Quote:
2) Im not sure if the foam pipe directs air to a sensor or if the sensor is at the dash and the foam pipe is merely encapsualting the wire..Soo I'm not sure.

On my system, foam pipe is an air pipe, no wires inside, connects 2 plastic tubes, 1 from sensor unit, other disappears into fenderwell.