Climate control CPU lockup and self distruction

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Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 5:44 pm

Much to my shock, while peacefully minding my own business on a mild 27c day in perth, out of the blue i could hear my heater valves activating at about 50hz for 5 seconds and then the air went hot. The AC and Recirc buttons had become non responsive and did not come back to life till I shut down and restarted the car, during this time the air sampling motor was also going mental even in fan position 0.

Its back to semi functional but has lost control of the hot water valves.

My side vents are incinerating the right side of my face while the center vents are freezing the left side.

Perhaps one of them has dead shorted and caused the disaster, I will check shortly.

My question is, is the climate control control unit isolated to the actual control panel - I know thats where the micro-controller is, is there anything else, ie is that where the solenoid switching transistors are ?

I will repair it - it is absolutely essential, the climate control unit is also what monitors coolant temperature and turns on the auxiliary cooling fans at 105c and at half speed for the aircon as required.
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Re: Climate control CPU lockup and self distruction

Post by Tony From West Oz » Mon 11 Jan, 2016 5:59 pm

On my '98 C250, the controls all appear to be in the back of the HVAC panel. I swapped one because it did not heat properly, and the heating worked better since then. Hope it is the same for your model also.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Mon 11 Jan, 2016 6:25 pm

MercMad West Australian wrote:Much to my shock, while peacefully minding my own business on a mild 27c day in perth, out of the blue i could hear my heater valves activating at about 50hz for 5 seconds and then the air went hot. The AC and Recirc buttons had become non responsive and did not come back to life till I shut down and restarted the car, during this time the air sampling motor was also going mental even in fan position 0.

Its back to semi functional but has lost control of the hot water valves.

My side vents are incinerating the right side of my face while the center vents are freezing the left side.

Perhaps one of them has dead shorted and caused the disaster, I will check shortly.

My question is, is the climate control control unit isolated to the actual control panel - I know thats where the micro-controller is, is there anything else, ie is that where the solenoid switching transistors are ?

I will repair it - it is absolutely essential, the climate control unit is also what monitors coolant temperature and turns on the auxiliary cooling fans at 105c and at half speed for the aircon as required.
Failure of these units is not uncommon and usually results in heater solenoid control issues, as you're experiencing.

You're also quite right in that the dashboard unit is the one and only control unit. I have a spare one from a wrecked car, along with a couple of heater duo valves should you need some items for fault finding.

Additionally I have an unserviceable unit from my old 230TE that lost control of the left heater. I'd be interested, if you can repair yours, to see if it can be economically repaired.

I've attached a wiring diagram for the system. It has all variations up to 8/89. Obviously not specific to your car, but have a look at approx page 13 for the 124.030 diagram. Most will be the same as yours except for possibly engine sensors etc.

cheers,
Trent
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 7:05 pm

Excellent,

Thanks for the quick replies. She is coming apart right now.

I'll update with my findings shortly once I get started and destroy yet some more clothing working on cars :rr:
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 7:28 pm

Duo valve failure, destroyed my control unit.

Passenger side solenoid winding just 2 ohms, practically dead shorted
drivers side 15 ohms.

Verified with bench power supply,

drivers side 800mA at 12.8v, loud and purposeful click.
passenger side, maxes out psu, 5.4A @8v soft click.

Feck!

Well I'm waiting delivery of my new radiator so it can wait till a brand new duo valve arrives too.

Now to pull apart control unit to see if salvageable.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 8:03 pm

Well both solenoids and a third device are switched by phillips BUK453-50A powerMOS transistors.

They're capable of switching up to 22 Amps and a surge of 88 Amps, however theyre not heatsunk in this control unit.

I will test them.

http://www.datasheetarchive.com/dl/Scan ... 100435.pdf
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Re: Climate control CPU lockup and self distruction

Post by Christo C » Mon 11 Jan, 2016 8:07 pm

In my '86 W124.023 / 230E, the climate control is partly controlled by the console switching unit as per your picture, but most of the work is done by a plug-in unit mounted below the Glove Box = TEMPERATURE REGULATOR MODULE N20 (behind/under GloveBox = remove glovebox first) - part no 000 822 15 03.
All the internal, external and heat exchanger Temp sensor wires, Duo Valve control, and Circulation Pump control wires run to that unit, and it also sends a control signal to turn the Aircon Compressor Mag Clutch On/Off via the Refrigerant Pressure Switch (next to receiver/dryer) and KLIMA Relay N6 (located behind Battery in engine bay).
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 9:51 pm

Christo C wrote:In my '86 W124.023 / 230E, the climate control is partly controlled by the console switching unit as per your picture, but most of the work is done by a plug-in unit mounted below the Glove Box = TEMPERATURE REGULATOR MODULE N20 (behind/under GloveBox = remove glovebox first) - part no 000 822 15 03.
All the internal, external and heat exchanger Temp sensor wires, Duo Valve control, and Circulation Pump control wires run to that unit, and it also sends a control signal to turn the Aircon Compressor Mag Clutch On/Off via the Refrigerant Pressure Switch (next to receiver/dryer) and KLIMA Relay N6 (located behind Battery in engine bay).

According to the wiring diagram it changed in September '87 to an all in one control unit / panel.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 10:17 pm

Well, being a bosch automotive part it, put up an enormous fight just to be opened and the board removed to be looked at.

transistors all test ok, big surprise, fault traces back to p.o.s. ceramic daughter board with no effort spared in concealing the tracks. Theres no further fault finding without an XRAY machine. Oh and its also all conformally coated in a rock hard varnish that smells like a festering truck stop urinal on a summers day when heated.

Joys.

I'll just get another one.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Mon 11 Jan, 2016 11:45 pm

new prices from pelicans in USD;

duo valve $295
control unit $445

Sad, very sad face moment.
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Re: Climate control CPU lockup and self distruction

Post by AMG » Tue 12 Jan, 2016 9:02 am

Got this one late..

ahh yes, as you have discovered it's all in the HVAC panel. Yes, they are conformal epoxy potted. No you cannot repair them economically.

JG *might* ?? have a 2nd hand unit, but maybe not.

One thing that also amuses me, is how many of them are never properly plugged back in when people remove the centre cluster to do stereo wiring etc. and this gives almost identical symptoms to what you encountered, except without the failed dead short in the duo valve.

exchange rate is not healthy at the moment and that is another reason the prices really suck. (apart from being screwed over because it's australia)
Current:
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 9:14 am

AMG wrote:Got this one late..

ahh yes, as you have discovered it's all in the HVAC panel. Yes, they are conformal epoxy potted. No you cannot repair them economically.

JG *might* ?? have a 2nd hand unit, but maybe not.

One thing that also amuses me, is how many of them are never properly plugged back in when people remove the centre cluster to do stereo wiring etc. and this gives almost identical symptoms to what you encountered, except without the failed dead short in the duo valve.

exchange rate is not healthy at the moment and that is another reason the prices really suck. (apart from being screwed over because it's australia)
I bought another original snow flake operation panel from Germany, $120 delivered, allegedly tested a-ok. Part number 124 830 19 85 with the snow flake AC button is NLA, the operation panel part number 124 830 29 85 with the EC button is interchangeable according to the EPC and is still available for $445 USD. (upto a certain chassis number only, then another operation panel is used.

I'll order a new duo valve next week.

It just renders my car undrivable at the moment, i hate driving with no aircon as the blast furnace that is the fully open heater is winning the battle with it currently. I should be receiving a new radiator this week anyway so I'll install the new duo valve at the same time that way i will only disturb the cooling system once.

I have nothing to loose now, I am going to remove the ceramic daughterboard and do my best to reverse engineer it.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 10:50 am

absolutely pi$$ing in the wind trying to repair the operation panel.

ceramic daughter boards filled with laser trimmed embedded passives and it could even be the customised motorola micro controller itself that's failed which you cant buy anyway. Bin Job.

out of interest, I will remove and test the 2 phillips electrolytic caps, one of which is for the 5v voltage regulator.
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Re: Climate control CPU lockup and self distruction

Post by Christo C » Tue 12 Jan, 2016 11:05 am

According to the wiring diagram it changed in September '87 to an all in one control unit / panel.
Yes, I forgot that....

Yeah it is a shame that "the blast furnace that is the fully open heater" is the default condition of a failed Climate Controller or Duo Valves - it always struck me as odd in Australia & Africa, though I imagine in some cooler climates a heater is more or less mandatory.

I just replaced the tiny DC motor inside the Ventilation Fan for the inside air temp sensor - a 12V 8100RPM motor Cat YM2716 @ $9.95 from Jaycar can be jammed into the case and slowed down with an external 27ohm resistor in parallel with 1000uF cap otherwise it is cyclonic. I can go and buy a new DVD player with the money I saved by not purchasing a replacement for the whole caboose.

Good luck with your repairs!
Last edited by Christo C on Mon 08 Feb, 2016 10:27 am, edited 2 times in total.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Tue 12 Jan, 2016 11:26 am

MercMad West Australian wrote:I bought another original snow flake operation panel from Germany, $120 delivered, allegedly tested a-ok. Part number 124 830 19 85 with the snow flake AC button is NLA, the operation panel part number 124 830 29 85 with the EC button is interchangeable according to the EPC and is still available for $445 USD. (upto a certain chassis number only, then another operation panel is used.
They are definitely interchangeable as I fitted an EC panel to my old 230 that originally had a snowflake panel.
MercMad West Australian wrote:upto a certain chassis number only, then another operation panel is used.
At some point they changed the heater box so that the centre vents can blow heated air. With that they changed the control panel (no doubt for temperature maps).
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 12:03 pm

Ahhh, so thats what the epc is talking about, from a certain serial number there is different behaviour of the central nozzle.

fyi, power transistors 1 2 & 3 are switched by outputs 1 2 & 3 via 10K resistors on each of ST LM2901 on left side of ceramic daughter board. I bet thats whats blown, if so, its easy to replace, i've already removed both the LM2901 and the LM2903 on the right bottom ceramic board with my smd hot air soldering station.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Tue 12 Jan, 2016 12:15 pm

MercMad West Australian wrote:Ahhh, so thats what the epc is talking about, from a certain serial number there is different behaviour of the central nozzle.
Mostly explained here, when you have spare time to get through this doc:
83-500 - Function description - air conditioner - automatic temperature control.pdf
Particularly the last page shows the different vacuum setup, with temperature mixing flaps etc.
MercMad West Australian wrote:fyi, power transistors 1 2 & 3 are switched by outputs 1 2 & 3 via 10K resistors on each of ST LM2901 on left side of ceramic daughter board. I bet thats whats blown, if so, its easy to replace, i've already removed both the LM2901 and the LM2903 on the right bottom ceramic board with my smd hot air soldering station.
:dance:

Have you determined what the third power transistor is switching? A/C Compressor perhaps?
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 12:23 pm

scorchi0 wrote:
MercMad West Australian wrote:Ahhh, so thats what the epc is talking about, from a certain serial number there is different behaviour of the central nozzle.
Mostly explained here, when you have spare time to get through this doc:
83-500 - Function description - air conditioner - automatic temperature control.pdf
Particularly the last page shows the different vacuum setup, with temperature mixing flaps etc.
MercMad West Australian wrote:fyi, power transistors 1 2 & 3 are switched by outputs 1 2 & 3 via 10K resistors on each of ST LM2901 on left side of ceramic daughter board. I bet thats whats blown, if so, its easy to replace, i've already removed both the LM2901 and the LM2903 on the right bottom ceramic board with my smd hot air soldering station.
:dance:

Have you determined what the third power transistor is switching? A/C Compressor perhaps?
NFI, its going to be either the recirc flap switch over valve or the air sampling motor in my opinion. I'm still on break from work till monday so i got plenty of spare time. I'll work it all out today and identify what each transistor switches in a diagram. :rr:

AC clutch is controlled by MAS relay on my car.

Output 4 on LM2901 appears to go no where too, only 3 of its 4 channels are being used.

Ordered the 2 LM ic's and will see what happens. I will make a pigtail lead to the back housing socket so i can probe the board on the car - again, way too much spare time, but loving every minute of it.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Tue 12 Jan, 2016 12:39 pm

MercMad West Australian wrote:NFI, its going to be either the recirc flap switch over valve or the air sampling motor in my opinion. I'm still on break from work till monday so i got plenty of spare time. I'll work it all out today and identify what each transistor switches in a diagram. :rr:

AC clutch is controlled by MAS relay on my car.
Had another look at the wiring and it appears the coolant circulation pump is also driven by the A/C control unit, perhaps that is what the third transistor is switching.
MercMad West Australian wrote:Ordered the 2 LM ic's and will see what happens. I will make a pigtail lead to the back housing socket so i can probe the board on the car - again, way too much spare time, but loving every minute of it.
:occasion5:
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 1:07 pm

scorchi0 wrote:
MercMad West Australian wrote:NFI, its going to be either the recirc flap switch over valve or the air sampling motor in my opinion. I'm still on break from work till monday so i got plenty of spare time. I'll work it all out today and identify what each transistor switches in a diagram. :rr:

AC clutch is controlled by MAS relay on my car.
Had another look at the wiring and it appears the coolant circulation pump is also driven by the A/C control unit, perhaps that is what the third transistor is switching.
MercMad West Australian wrote:Ordered the 2 LM ic's and will see what happens. I will make a pigtail lead to the back housing socket so i can probe the board on the car - again, way too much spare time, but loving every minute of it.
:occasion5:
Think your onto something there, its tracks are very beefy and thats a big motor.

transistors on bottom left, starting at left: Left duo valve, right duo valve, and third, still investigating but i suspect your right.

***Edit, yes, you are right. Transistor 3 is coolant pump
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 3:24 pm

After spending the entire day searching for an MB wiring diagram for the tempmatic system from 1987 that isnt an absolute illegible disgrace, I found one!

but its in german, but who cares, you can use the legend from the english version.

One for the archives
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 3:59 pm

I made this visual pinout of the connector too since MB diagrams are without exception, always rubbish.

Compressor request from operation panel is carried through pressure switch S31/1, if the gas is low, the request is blocked.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Tue 12 Jan, 2016 4:34 pm

MercMad West Australian wrote:I made this visual pinout of the connector too since MB diagrams are without exception, always rubbish.
Ok, now you're proving you have too much time on your hands :whistle:
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 4:56 pm

I'm done for today :wave:

Todays research has paved the way for future possibilities.
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Re: Climate control CPU lockup and self distruction

Post by Ivanerrol » Tue 12 Jan, 2016 7:38 pm

There was a DIY out on the net where someone repaired the coils in the duovalve. It's been lost unfortunately.
Allegedly it's only the first few windings that get spoiled by coolant leakage.
Unwinding the coils a few turns generally discloses the faulty wiring. Cutting off this faulty wiring and re-soldering back to the terminal has fixed the s/c.
If you have the time, this may or may not be a solution rather than paying out big buckeroos for a new Duovalve.
Alternatively there are plenty of second hand Duovalves out on feebay with faulty valves and good coils that maybe had for not much $$$
Getting a spare for free is much better. :wave:

I recently drained the coolant from my W202 and cleaned out the duovalve. The duovalve was gunked up and wouldn't close 100%. The AC was struggling against that little bit of heat that was getting through the valves. - Much better now.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 12 Jan, 2016 9:00 pm

Last week i disposed of a bmw with duo valve solenoids that looked remarkably similar. I let them goto the crusher under the assumption im never going to need those.
$245 for duo valve from pelican parts, i always assumed they were much more expensive ie, $700+ for a genuine mb article


Now whats the chance of my 26 year old hot water pump crapping out and destroying another operation unit.?
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Re: Climate control CPU lockup and self distruction

Post by Ivanerrol » Wed 13 Jan, 2016 10:40 am

Hi M.M.W.A.
I have this - A.F.A.I.K the valves are broken but the coils are good. If you want to pay the post from Melbourne it's yours - if its the same as your one.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Wed 13 Jan, 2016 11:49 am

MercMad West Australian wrote:After spending the entire day searching for an MB wiring diagram for the tempmatic system from 1987 that isnt an absolute illegible disgrace, I found one!

but its in german, but who cares, you can use the legend from the english version.

One for the archives
Here you go :glasses2:
83-2 Automatic Temperature Control 124.031 from 09-89.pdf
83-16 Automatic Temperature Control 124.031 from 08-91.pdf
Without wanting to tread in Les' toes, I also have a couple of spare duo valves in working order. You're welcome to one if you want to pick it up from me. PM if interested.

cheers,
Trent
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Wed 13 Jan, 2016 12:49 pm

Thanks guys - I'm gonna try source a new one first, I'll fallback to the used option if NLA.

Regards to the diagrams, BRILLIANT!

Theyre the first ones on the internet anywhere in such quality. Congratulations. Even the WIS has the rubbish version ultra low resolution, illegible diagrams. Someone at MB needs severe punishment.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Wed 13 Jan, 2016 1:09 pm

MercMad West Australian wrote:Theyre the first ones on the internet anywhere in such quality. Congratulations. Even the WIS has the rubbish version ultra low resolution, illegible diagrams. Someone at MB needs severe punishment.
The documents on WIS are taken from microfilm (which are even harder to read) and also don't encompass all models. The full, accurate and easy to read diagrams were always in paper format, right up to about 1995 (W210 was the first to have full diagrams in WIS). All dealers had them so it wasn't an issue to not transfer them to WIS.

For the W124, there's SIX A4 files of wiring diagrams:
File 1: Main vehicle diagrams for models up to 08/89
File 2: Specific (optional) equipment diagrams for models up to 08/89 (Central locking, A/C etc.)
File 3: Main Vehicle diagrams for models from 09/89 to 08/92
File 4: Specific (optional) equipment diagrams for models from 09/89 to 08/92
File 5: Electrical groups 01-54* for models from 09/92
File 6: Electrical groups 54-91* for models from 09/92

*Can't remember the specific split point...
Last edited by scorchi0 on Wed 13 Jan, 2016 1:19 pm, edited 1 time in total.
1991 S124 300TE - Smoke Silver
1993 C124 320CE - Brilliant Silver
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MMWA
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Wed 13 Jan, 2016 1:14 pm

so, you have this paper manual eh ?

I wouldnt mind borrowing it, I can scan the whole document and convert to PDF, even if its in a book I got plenty of time ;)
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Wed 13 Jan, 2016 1:22 pm

Fellow 6.9 owner nutjob nathan, climbed into the dumpster at diesel motors when they moved and retrieved cartons of old manuals along with a brand new R230 steering wheel - I scanned all of them for him. Many of them even had unobtainium material specifically for the 6.9 too.
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Re: Climate control CPU lockup and self distruction

Post by scorchi0 » Wed 13 Jan, 2016 1:26 pm

MercMad West Australian wrote:so, you have this paper manual eh ?

I wouldnt mind borrowing it, I can scan the whole document and convert to PDF, even if its in a book I got plenty of time ;)
Just edited my post above. BTW each diagram is a separate insert in the file, which is usually A3 and a half, if that makes sense...

Oh and they're double sided.

I know Nathan and I can just imagine him doing that. Interesting to know that DM ditched all of that. But then, when was the last time they would have seen a 6.9, let alone anything pre-2000?
1991 S124 300TE - Smoke Silver
1993 C124 320CE - Brilliant Silver
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Re: Climate control CPU lockup and self distruction

Post by Christo C » Wed 13 Jan, 2016 5:26 pm

Any chance to get a peek at
File 1: Main vehicle diagrams for models up to 08/89
File 2: Specific (optional) equipment diagrams for models up to 08/89 (Central locking, A/C etc.)

?
~Christo
1986 230E W124.023 M102.982 Thistle Green Saloon "Janis"
Beaconsfield, SYDNEY

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Re: Climate control CPU lockup and self distruction

Post by MMWA » Wed 13 Jan, 2016 10:06 pm

worm can, officially opened :rr:

I'd love to get a copy of absolutely everything, too.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Tue 19 Jan, 2016 7:21 pm

If anyone is as analy retentive as me and only demand new parts,

I've had the DUO valve added at FCP euro if you want to buy a new one - their shipping is cheaper than pelicans, and particularly so on heavy items as they use a similar if not the same as the pitney bowes service on eBay. Ie it avoids the LA the NSW leg of the journey which is the most expensive part and goes upto Alaska and then over to Japan and down. So it does take longer, but who cares.

https://www.fcpeuro.com/products/merced ... 0008306584

I dare not ask what they cost in Australia ;)
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Wed 03 Feb, 2016 10:38 pm

This brand I had never heard of prior to today.

Perhaps a new supplier to MB, my original duo valve was Bosch

http://en.sitronic.com/company/

IMG_2215.JPG
The OCD in me isn't too pleased about the misaligned logos.
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Re: Climate control CPU lockup and self distruction

Post by Waz » Thu 04 Feb, 2016 12:34 am

I repaired my aircon one year ago almost to the week on a 300CE (1989). I live in Cairns, and as a "sort-of" Queenslander I try (and fail) to be Quite Hard and pretend from time to time that I live without air conditioning. I feel your pain. I paid a procession of Eager Gentlemen a total of $Verymuch to "repair" my air conditioning system including eventually (after a bit of a bodgethon) presenting myself, tail between my legs, at the local Mercedes Benz stealership to have it "done properly". After they had finished laughing, they repaired the air conditioning system by completely dismantling and re-assembling the car and presented me with a Very Large Bill. I actually can't bear to recall how much it was, but labour alone was about $2,600. (Evap, heater matrix, compressor.. I think it was $4k+)

The job was a good'un. One year later, I can produce internal temperatures that cause external condensation on all windows at normal cruising speed. I have to wipe condensation off the rear-view mirror, steering wheel, and any passengers after the door is opened.

If the aircon had not been fixed I would have scrapped the car.

It is OK to have a quiet weep when no-one is looking over the cost of repairing the aircon. I now laugh in the face of the cylinder head gasket. I dare your reverse gear brake band to exhibit slight signs of wear. No timing chain cover oil weep will keep me up at night. Not any more.
Mercedes-Benz C124 (300CE)
WDB1240502A94****
M103.983 (12-valve)
G722.358 (4-sp auto)
251k kms
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Thu 04 Feb, 2016 9:54 am

Not sure I mentioned it, but i got a used tempmatik operation panel from germany of the same part number - restored it with the housings off mine as it looked terrible and tested it out.

All is operational now and it is trying to control the currently disconnected duovalve.

I will finish the job on the weekend if i have time - new radiator install, duo valve and finish off assembling the centre console. I want to clean the fan speed knob contacts while its apart as it only occasionally works on position 1 and thats my favourite speed. Anything more blows a gail or freezes my face.

I'm also in the process of having a vehicle hoist installed in my backyard as im too old, stiff and fat to roll around under cars anymore. Sh#ts getting real.
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Re: Climate control CPU lockup and self distruction

Post by MMWA » Sun 07 Feb, 2016 10:08 pm

fully functional AC has been restored.

I'm not convinced the newly manufactured valve will last as long as the original Bosch unit.

Had the car running in my 40c shed for about an hour while i sat inside it and messed around with T5 LED wedges and reassembled the centre console in airconditioned comfort. By the end of it, I just so happend to touch the new solenoids to see how hot they run, and sure as hell they're hot enough to burn your skin.

Unimpressed. Obviously in lame euro climates it might be fine where it never gets hot like it does in perth, the valves will cycle instead of being energised closed 100% of the time like they are in a perth summer. :wall: The sitronic duo valve consumes more energy in operation than a functional original bosch unit too. Fail MB, fail. Though it is practically silent in operation which is a nice change. The original unit I could hear clunking away from inside the car.
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Re: Climate control CPU lockup and self distruction

Post by ghipl » Sun 21 Aug, 2016 2:26 am

Hi Guys,

It's been a long time since I've ventured onto this forum, much to my disgrace. Have been very busy over the last several months, but did manage FINALLY to get my much loved but rather neglected "Old Girl" ('86 300E) all road worthy, registered and on the road a couple of weeks ago. Very happy and relieved to have finally achieved that, after having her off the road for about 9 months. Needed her badly.

I have sorted out most of the major issues, but still have a quite a long list of less critical, but no less important ones to go. Most of them electrical. Hence my interest in any of your posts dealing with electrical issues.

One of the major issues I'm having is finding reliable circuit diagrams for the 'Old Girl'. It seems that I'm not alone in that dilemma either, as I get the impression that most of you out there are in the same boat.

I noted with interest the entry under this thread, that mentions 6 files of A4 circuit diagrams published for the W124 series. It goes without saying that I would dearly love to get my greasy hands on copies of Files 1 & 2. I take it from the drift of the post, that this list refers to paper files issued to Mercedes Dealers, and not to files available on WIS? I have access to WIS files for the series, through 'emanualonline', but find it very difficult finding specific information for my exact model. I don't think I've come across a single circuit diagram in all my searching through that resource. Need to just keep looking I suppose, but it sounds like they may not be of much use to me if they are 'unreadable', as your posts seem to suggest.

This may be a silly, perhaps stupid question, but is it worth approaching MB dealerships, to see if they still have access to these diagrams, and if they're willing to part with (or supply) some copies?? Does seem like a really stupid question actually, as I'm certain most of you have probably done that long ago and drawn a blank, otherwise you wouldn't be like me and still looking for reliable circuit diagrams.

I came across a chap in Toowoomba recently who has been working on Mercs for well over 40 years, so I might pay him a visit sometime soon and see what he has in his archives. He didn't seem that 'electrically inclined', but you never know your luck.

Spoke to the guys at MB Spares a while ago re this 'problem' and they said that there used to be a good workshop manual around for the Aussie version of the W124, with good circuit diagrams, but it went out of print several years ago. Knew I should have bought a Merc years ago!!

Anyway Guys, nice talking to you all again. If anyone does come across a few good circuit diagrams for an '86 300E, I'd really appreciate a post. I'll try and make a habit of checking up on you guys more often, but I'm getting a bit old for this 'burning the midnight oil' stuff too often. Only time I get to do much research lately I'm afraid.

Ah - One day I might discover what this 'retirement' business is all about.

Cheers Guys

Gary (ghipl)

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Re: Climate control CPU lockup and self distruction

Post by MMWA » Sun 21 Aug, 2016 9:50 am

Having met mr scorched in person, I can confirm his collection of documentation is second to none.

Actual physical manuals and even microfilm with a vintage viewer (but not printer).

You see, owning an MB stealership in the 80's had its benefits ;)

If you ask him nicely he may provide the docs you seek, or tell you where to go, its entirely upto him :P
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Re: Climate control CPU lockup and self distruction

Post by dennisr » Thu 04 Oct, 2018 7:44 pm

MMWA wrote:
Tue 12 Jan, 2016 9:14 am
AMG wrote:Got this one late..

ahh yes, as you have discovered it's all in the HVAC panel. Yes, they are conformal epoxy potted. No you cannot repair them economically.

JG *might* ?? have a 2nd hand unit, but maybe not.

One thing that also amuses me, is how many of them are never properly plugged back in when people remove the centre cluster to do stereo wiring etc. and this gives almost identical symptoms to what you encountered, except without the failed dead short in the duo valve.

exchange rate is not healthy at the moment and that is another reason the prices really suck. (apart from being screwed over because it's australia)
I bought another original snow flake operation panel from Germany, $120 delivered, allegedly tested a-ok. Part number 124 830 19 85 with the snow flake AC button is NLA, the operation panel part number 124 830 29 85 with the EC button is interchangeable according to the EPC and is still available for $445 USD. (upto a certain chassis number only, then another operation panel is used.

I'll order a new duo valve next week.

It just renders my car undrivable at the moment, i hate driving with no aircon as the blast furnace that is the fully open heater is winning the battle with it currently. I should be receiving a new radiator this week anyway so I'll install the new duo valve at the same time that way i will only disturb the cooling system once.

I have nothing to loose now, I am going to remove the ceramic daughterboard and do my best to reverse engineer it.
Hi, how do I find out what the part number would be for my climate control unit in a 1988 300CE, W124.050, 3.0L, 12 VALVE?? Oh and my car has a broken heater control valve, but it is a duo valve, a sitronic one. But when I put my model into Pelican parts it says it should be a single valve type....one pipe in one pipe out. Mine is one in two out. Can I put a single in or do I have to use a duo valve?
thanks
Dennis :dontknow:
1988 MB 300CE M103.983 VIN:WDB1240502A674200

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Re: Climate control CPU lockup and self distruction

Post by Christo C » Fri 05 Oct, 2018 6:29 am

dennisr wrote:
Thu 04 Oct, 2018 7:44 pm
... when I put my model into Pelican parts it says it should be a single valve type....
Many variants were not imported or sold in USA, esp 4 cylinder models, therefore do not appear in US databases; best to determine Part Number and shop on that basis only.
dennisr wrote:
Thu 04 Oct, 2018 7:44 pm
... Can I put a single in or do I have to use a duo valve?
I suppose you could plumb in a single valve, but that would make a nonsense of the dual L & R system in the cabin. Best to replace with correct part imho.

Also, it is worth looking around in Australia - there are quite a few Mercedes Parts Independent importers

e.g. Silver Star Spares in Kingsgrove NSW 02 9554 3835

also in UK e.g. https://www.autodoc.co.uk/car-parts/oem/0008306584
~Christo
1986 230E W124.023 M102.982 Thistle Green Saloon "Janis"
Beaconsfield, SYDNEY

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Re: Climate control CPU lockup and self distruction

Post by dennisr » Fri 05 Oct, 2018 2:24 pm

Thanks Christo!
1988 MB 300CE M103.983 VIN:WDB1240502A674200

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