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  #16  
Old 08-24-2004, 02:49 PM
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Quote:
Originally Posted by Arthur Dalton
I see no s25/5 , but s25/11 feed from 12.

There is an idle rpm ,min 600rpm, with a 10 sec delay input at pin2.
Do you show that?????????/
Okay. S25/11 & S25/5 as well as S25/3 are quasi same function just different engines and/or years.

My pin #2 goes to X29/4 (1-pole test coupling) and then to N8 (Control Unit - Idle Speed Control). This N8 has the K1 overvoltage relay, L3 Starter Ring Gear RPM Sensor, and two ELR related devices connected to it. Not certain how the Idle Speed Control Unit works into the overall scheme of things. Actually, I haven't even located it in my vehicle yet.

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  #17  
Old 08-24-2004, 02:56 PM
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I am not familiar with that RPM circuit .
My schematic says it was phased in from 87-88..
SB prolly knows more on that [ or MBDOC]

I am assuming you do have the car running when checking the other switch disconnect test...
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  #18  
Old 08-24-2004, 03:04 PM
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Yes on the running while performing the tests.

The one thing that keeps making me wonder is that where most people use the Ice-Cube Relay to bypass the Klima and solve their ACC problems, mine won't engage the compressor when it is installed. That has to be some type of indicator.
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Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.
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  #19  
Old 08-24-2004, 03:14 PM
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So ,
where exactly does the ice cube line up with the pin3s and which are primary [ coil] and which are contacts [ load ] on ice?
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  #20  
Old 08-24-2004, 04:38 PM
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Quote:
Originally Posted by Arthur Dalton
So ,
where exactly does the ice cube line up with the pin3s and which are primary [ coil] and which are contacts [ load ] on ice?
Pin #3 on the Klima socket is not used by the Ice-Cube relay. The only Klima socket pins used are 1, 5, 7, & 10. Actually, pin #3 on the socket does not have a female receiver but rather a blank hole. That seems strange to me since the Klima has a pin at #3. So the complete line-up is 1 > 85, 5 > 86, 7 > 87 & 10 > 86. That's all the "recipe" calls for when doing the conversion.
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'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
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  #21  
Old 08-24-2004, 07:16 PM
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Please bear with me . . .
Klima socket #s followed by Klima designations

1 = 31 ground to battery
2 =GM+ testing post > idle speed control, Control Unit
3 = TD not used
4 = VL
5 = 15 > 12 pin connector > auxillary fan relay
6 = 87k to kickdown switch
7 = 87 to compressor's k1 which is the electromagnetic coupling
8 = no pin
9 = GK+ to compressor's l1 which is the RPM sensor
10 = KL to pressure switch, refrigerant compressor, OFF 2.0 bars/On 2.6 bars
11 = GK- to compressor on the RPM sensor side
12 = T to S25/5 Temperature switch 115 degrees C for compressor/emergency cutout


The 10 amp fuse is fine on the OVP.
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'87 300TD - 132K - Soon 4-Sale
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  #22  
Old 08-24-2004, 07:33 PM
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I have that info
I meant :
What pins on the ICE CUBE relay are coil and what are Contact switch??
The coil pulls in the contactor , so we know we need the contactor on pins 5 and 7 to get power to the C Clutch.

So, I need to know which are coil/contactor on ice..not on klima
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  #23  
Old 08-24-2004, 10:08 PM
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Quote:
Originally Posted by Arthur Dalton
I have that info
I meant :
What pins on the ICE CUBE relay are coil and what are Contact switch??
The coil pulls in the contactor , so we know we need the contactor on pins 5 and 7 to get power to the C Clutch.

So, I need to know which are coil/contactor on ice..not on klima
Not being certain what signifies the coil/contactor I am going to try to provide a readable schematic below:

86 87 87a
o---, o o
| [=/=]-->-------/
o---' o
85 30

The [=/=] appears to be the coil??? Pin numbers are above & below the "o" pins. Pins for 86 & 85 tie to the [=/=] using , & ' respectively.
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Last edited by BrierS; 08-24-2004 at 10:16 PM.
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  #24  
Old 08-24-2004, 10:11 PM
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After posting above, I noticed the spaces are not present between 86, 87 & 87a so you need to visualize them being spaced in accordance with the "o" pins.

If I am reading the schematic correctly, 86 & 85 are coil, 87 = ? while 87a & 30 are the switch.
Steve
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'87 300TD - 132K - Soon 4-Sale
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  #25  
Old 08-24-2004, 11:11 PM
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I think you need a relay that will put the coil across pin 5 and 10.
That way , when the PB is operated it will give the coil ground and complete the circuit [ through the pressure sw and PB unit.]

So, when this happen , the coil will pull in the contacts , which are wired across pin 5 and 7. This will power the clutch.
So, you see that pin 5 is common for both coil B+ and clutch B+.
Whereas , pin 10 is B- for the coil and and 7 is the closing of the relay to feed power from 5 through 7 to clutch.
If you draw this on the schematic , you can see how it works . [ coil across pin 5 and 10, switch across pin 5 and 7]Then you just have to make sure the ice cube inside wireing is applicable to place the coil and contactor pin in the correct places .

Pin 1 is a ground and not needed in this circuit, as you want to catch ground through PB and pressure sw.

UI think there are 2 different type relays , depending on ground switcin g or power switching

Here is an example :


GERMAN AUTOMOTIVE
Junior Member Join Date: Mar 2000
Posts: 14

THE COMPRESSOR RELAY CAN BE BYPASSED AS FOLLOWS,USING RELAY # 001 542 02 19 MAKE YOUR OWN JUMPER WIRES. TERMINAL #1 ON KLIMA TO #85 ON ICE CUBE,#10 KLIMA TO #86 ICECUBE ,TERM. #5 KLIMA TO #30 ICECUBE,AND #7 KLIMA TO #87 ICECUBE. CLUTCH WILL ENGAGE AND DISENGAGE AT PUSHBUTTON ASSY'S COMMAND.M.F.
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  #26  
Old 08-25-2004, 12:25 PM
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Arthur,
I re-ran the series of test at the Klima socket because I remembered the last test involved the speed sensor and I was uncertain of the result. According to the service manual testing the voltage (in AC not DC) at terminals 1 & 2 should give > 3.8 volts at about 750 RPM and should increase the voltage as the RPMs are increased. I just measured it again and confirmed what I had thought I found the first time. The voltage starts at or about battery voltage (hard to tell since I am in AC voltage mode) and stays that way through out the RPM range. Any idea how I can safely bypass the speed sensor?
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'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
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  #27  
Old 08-25-2004, 12:44 PM
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The only way I know is with the ice cube relay.
The problem, as I have mentioned , is some PB units feed power to the klima and some ground the klima. [ at pin #10]
So which relay is used depends on the PB switching.
If pin 10 is a switched ground [which I think yours is, as you stated neg reading ] then the relay uses pin 10 for the ground side of the relay coil.
If the PB #10 terminal is a power feed from the PB , then the ground for the relay coil is grabbed at pin # 1.
So, 2 different systems that will require different relay internals

here is a link that MBDOC has post in regards to rpm bypass.
I am not fimiliar with that circuit have no info to check into it..

A/C RPM sensor bypass
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  #28  
Old 08-25-2004, 01:36 PM
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Steve -

Have been too busy to respond of late, apologies for the delay.

I believe your ice cube bypass is improperly wired. Arthur has identified the correct solution in his text, but the instructions he has quoted from a previous post apply to a gasser; diesels, for some mysterious reason only understood in Stuttgart, operate differently. I have successfully built and used an ice-cube bypass for my '87 diesel, though it has been a few years.

In general, a gasoline 124 sends +12v to pin 10 of the Klima as the signal to operate the compressor. Your diesel grounds pin 10 of the Klima socket to signal operation of the compressor. Use your DVM to check voltage between pin 5 & 10 with the a/c switched off, then on. I expect you to see indeterminate voltage during the first test, and a solid 12v on the second.

If so, modify your ice cube bypass as follows: pins 85 & 86 (the relay coil) connect to pins 5 (+12v) & 10 (PBC ground signal) on the Klima socket. Not sure if it matters which Klima pins are connected to which relay pins. If it doesn't work, try swapping pins 85 & 86 on the relay - some relays are sensitive to the direction of current flow.

Pin 30 on the relay is also connected to pin 5 (+12v) on the Klima socket. Pin 87 on the relay is connected to pin 7 (compressor coil) on the Klima socket. Pin 87a on the relay is unused.

So if it is all working correctly, when you push the a/c button in the cabin, the PBC grounds pin 10 of the Klima socket. Since pin 85 of the relay is now grounded, and pin 86 is connected to 12v, the relay activates. This connects 12v at pin 30 of the relay to pin 87 of the relay, which then sends +12v to the compressor clutch. The compressor switches on, you get cold air and a smile on your face.

A couple of notes on the bypass circuit. You will of course lose the RPM comparison compressor cutout circuit. Whether this is a bug or a feature I will let you decide. Having had a compressor seize up while crossing the west Texas desert, I rather like it.

You will lose the high temp cutout circuit. The Klima relay shuts off the compressor when engine coolant reaches 115C degrees. Of course, you can monitor the coolant temp and take care of this manually. Shouldn't ever happen in a properly operating car.

You will lose the full throttle compressor cutout. So you stay cool while passing, but it takes longer to pass. You can always switch to E/C before accelerating around slower cars.

Finally, the transmission kickdown will be disabled. At higher speeds the car will no longer drop into 3rd gear when full throttle is applied. You'll notice the Klima relay is actually labeled "Klima+Kickdown."

I ran the ice cube bypass for a few months, but decided to replace it with a fresh Klima once things were sorted. I had multiple problems triggering the compressor cutout: excessive air gap on the compressor clutch (due to normal wear), plus grease and oil on the compressor clutch surfaces. These two problems caused enough slippage to trigger the cutout circuit on the Klima relay. After fixing these issues, I reinstalled the original Klima. The compressor no longer cutout, but would switch on & off in a rapid, random succession. I ordered a new Klima relay, and all has been well since. I think all that diagnosis and work was in the summer of 2000; not exactly sure.

Guess my point is this: Klima relays do go bad. They do more than just switch on the compressor, so I see the ice-cube bypass as a temporary/diagnostic fix.

My $.03 (long post...)

- JimY

quick edit: Here's a link to a site with ice cube schematic & explanation: http://www.teamrocs.com/technical/pages/relay_basics.htm
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  #29  
Old 08-25-2004, 10:05 PM
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jcyuhn,
Did you check Arthur's photo sketch? If you were in my place would you think he didn't like my computer (keyboard special) drawing?

Kidding aside, thanks to both of you. I got as far as attempting to check the voltage actions of terminals 5 & 10 with my TWO meters. The first one is a meter I bought about thirty years ago when I owned/operated a service station. It relies on the battery for the primary + & - leads and provides a voltage + clip/probe and one for testing ohms. Being digital, I tried to use the negative cable on terminal 10 but the meter won't work that way. So I hooked it up to the battery as I normally would and individually tested 5 & 10 just to see if voltage was present. I was surprised to find 0.34 volts at 10 while battery voltage was at 5. Next I used my little muti meter knowing it would not allow for small voltage readings. However, it does work directly with two probes. I checked with 5 (+) and 10 (-) and got the desired results switching the PB Controls on and off of AC. I will need to redo my ice cube wires tomorrow since my old bulldog suddenly showed signs of distress. He has a bad heart and has had three conversions. Being my best pal his last days find me staying as near as possible (hated to travel to Manchester today). Sorry for the long explanation yet I wanted to let you know I really appreciate the help and also that I am moving as quickly as possible to follow the advice. By the way, ultimately I want to find the problem and go back to the Klima. I am not so concerned with the risk of undetected compressor failure since I am very accute to any changes in noise and other operational issues. Kickdown is nice and the extra power under full throttle likewise, however in the meantime AC would be better.

I need to find and read (I have the CDs, MB Climate manual, and Haynes) the procedures for checking the compressor clutch gap and acceptable cleaning methods. Typically I use electromotive cleaner for anything electrical but I am not certain if it is advisable on AC (never watched any of my mechanics working on AC when I had my station). I love doing this stuff and wish I had another eight weeks straight of vacation (just finishing my eight) to keep sorting. Okay, too long. Its been one of those days and Brier (bulldog) isn't up to eating so he certainly doesn't want to listen/read my ranting.

I'll keep you posted and thanks again.
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Steve
'87 300TD - 132K - Soon 4-Sale
'84 300D Turbo - 122K - Driving
'77 VW Type II - 77K - Restored
'08 250EX Ninja
English Bulldog (Brier) - My best friend. Passed away 12/02/04 while in my arms.
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  #30  
Old 08-26-2004, 11:31 AM
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Being a "dog person", I sure understand your priorities.

Checking clutch gap is easy - just use feeler guages such as for valve adjustment or spark plug gapping. The clutch air gap is supposed to be 0.50mm, plus or minus some small amount that I cannot remember.

There are lots of options for degreasing the clutch. Brake parts cleaner would be one. Think I used a citrus degreaser intended for bicycles, rinsing with water. It's not rocket science, you just need a method to get it down into the clutch gap.

- JimY

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