Got an 85 300 D with a possible bad klima. All other problems are sorted out with the A/C so this is the last "weak link"

Does anyone know the proper procedure to test this before I spend way too much money on a new one??

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Here's one approach:

Dear God, is there a way to determine if this problem is the Klima or not?

Use SEARCH facility - key in KLIMA and Titles Only. Many hits

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

I have been searching for HOURS. Yes I use the "search" feature BEFORE I post a question. Most of the threads are NOT relevant to my specific delima.

I need to know how to test the Klima on my 85 300 D.

The pin numbers etc change from year to year.

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Would be happy to fax that test! Leave that fax number here or send me private message.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Hey MB DOC,

My fax number is 206-237-7390

The pins on my Klima part number 001 545 74 05
'85 300 D

87, 15, 31 on one row
KL, 87k, VL, GM+ on the other row

Thanks so much for your help!

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

The only true way to test is to replace. I had bad solder connections on my board, resoldered but it still would not work so I bought new and wala its working.

To test:

Pin 31 is ground
pin 15 is B+ 12V when ignition is on
pin 87 is out to compressor.

KL ? Speed
87K ? speed
VL ? climate control
GM+ ? engine speed
Not sure which is which but I do know that you have a speed reference signal from your speed sensor in back of the compressor on 2 of those pins. One other is connected to your engine speed reference signal on mine its "TD" and the last is from your climate control module.

To test Kilma;
Remove and jump 87 and 15 and see if compressor comes on. If compressor not on check fuses, wiring and connections to compressor. If so then check signal from speed sensor should be 0.2~0.4Vac across the 2 wires coming from the sensor not ground. Check speed sensor. You also have a microswitch somewhere under air cleaner box connected to the throttle linkage, it is used to cut off compressor when you give full throttle.
If all checks ok I would open relay module and check for bad solder connections. This is a common problem.

My first posting - hope this is correct - but Dieselgiant, what else have you replaced in the entire A/C system? I'm struggling w/ a similar problem (new compressor, new controller, good gas pressure) but still no compressor "on".

That would be a sweet noise to hear right now. Any info is appreciated.

I am getting the power problem fixed before I dive into the A/C mechanicals. At the very least I must pull a vacuum and verify no leaks. I already put 12 volts to the compressor clutch with jumper wires and she fired right up with no problem. If I have no leaks, then I will probably flush, new oil, drier and expansion valve, freon. However I must get the electrical sorted out first.


Ok I have B+ 12V at pin 15.

I jumped 87 and 15 and got 12V at compressor.

I have signal across speed sensor pins that increase smoothly with RPM.


Since the system has no freon I have the 2 wires jumped at the low pressure switch with a paperclip. If I remove the paperclip and still jump 87 and 15 the compressor still gets power.

How can this be?

I may have 2 seperate problems. I would think that since pin 15 is hot with key on, applying power to 87 just verifies the wiring etc is good to the compressor.

Still not sure Klima is bad.

I guess I dont understand if the power goes to the Klima then to the low pressure switch or vice versa.

I would assume the flow of power must go to the low pressure switch first, then to the klima or somewhere else to energize the compressor.

I hate electricity! Rebuilding the mechanicals of the A/C system is a breeze compared to chasing down an electrical prob. I never was real good on electrical things. But I am learning real fast now

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Power is started when ignition is turned on thru
Take it all back I don't have schematics in front of me here at work.


I do know that what I stated prev. is the correct procedure for testing


If compressor comes on when you jump out the relay and you have a good speed sensor signal(with a continuity tester check the wires from speed sensor to the Kilma relay connectors. You can find which pins go to what) Also check the microswitch under the air filter box for continuity( press the switch in several times while checking to make sure its good.) And you have the engine speed signal, then I would suggest replacing the relay ... You can find one here (cheapest price I have found) http://thepartssite.com

Also very important. You must have the blower on max temp set to min and AC on to do this test correctly
good luck

Anthony