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  #1  
Old 08-15-2008, 04:04 PM
777funk's Avatar
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Klima Relay Deleted om603

THIS IS NOT IN THE SHOP MANUAL

Here's what I did because I was tired of issues with my a/c.

See pics.

Basically omitted the Klima Relay circuitry that compares the engine speed with the compressor's speed, checks engine temperature, and one or two other things. Now the compressor comes on when I turn on the A/C in the car. The only IF condition that has to be met now is that the Pressure switch on the dryer has to be closed (enough freon).

I've now got the same setup as the w123 before 85. I have to watch the gauge for over heating but I do that anyways so I'm not worried. And I won't have to mess with the A/C electronics EVER again. Hopefully...

But here are the pics.

Steps:
1. Remove Klima Relay cover (clips on side-open w/flat screwdriver). I cut mine but I realized later didn't have to

2. Unsolder the old board (solder wick or solder sucker)

3. Solder the GND signal from Climate Control Unit which is pin #10 on the Klima relay socket to one side of the new Relay's control coil

4. Solder the +12V supply (Pin 5 of the Klima socket) to the other side of the new Relay's control coil and also to the Normally open side of the new Relay's switch.

5. Solder the "to Compressor" 12V supply signal on the Klima (Pin #7) to the other contact of the new relay. This way when the new relay switch closes it'll send 12V to the Compressor's clutch coil.

Now... No more need for the Klima Relay. My relay was $3 on ebay. I used a 30 or 40A relay but I'm guessing the A/C clutch coil only draws 1A or 2Amps.

So... now I'm the brain instead of the Klima relay. I'll be listening and watching a little more. But I'll not have to work on the A/C circuitry for a long time and I saved about $200.

Attached Thumbnails
Klima Relay Deleted om603-dsc_0002.jpg   Klima Relay Deleted om603-dsc_0007.jpg   Klima Relay Deleted om603-dsc_0006.jpg   Klima Relay Deleted om603-dsc_0003.jpg  
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  #2  
Old 08-15-2008, 04:24 PM
compress ignite's Avatar
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Yes, and you'll monitor the A/C compressor "LockUp" How?

'Without the Dreaded Clima (Or Klima as we call it) ,the Compressor is free to
"Lock-Up" and snap the serpentine belt with you none the wiser...Oh ,That's
right you're gonna be watching your Temp Gauge (and praying over it's
accuracy) instead of the Roadway...Because that is the kind of vigilance you
will have to devote to saving your engine.
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  #3  
Old 08-15-2008, 05:09 PM
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Quote:
Originally Posted by compress ignite View Post
'Without the Dreaded Clima (Or Klima as we call it) ,the Compressor is free to
"Lock-Up" and snap the serpentine belt with you none the wiser...Oh ,That's
right you're gonna be watching your Temp Gauge (and praying over it's
accuracy) instead of the Roadway...Because that is the kind of vigilance you
will have to devote to saving your engine.
True, true... but I'd bet the Belt would squeal like a pig for a few minutes before it breaks. Also... you're forgetting that the alternator can also seize up... as could the water pump or power steering pump. None of those are monitored by an electronic baby-sitter as the Compressor is.

We had the Alternator seize this year. My wife came home one day and said that the car sounded like there was a motorcycle under the hood. She ran it about 5 miles with the sound (according to her word). When she got home and told me about the problem, I looked at it while it was running and the belt was squealing away. The engine was still turning just fine but the alternator was seized dead in its tracks not moving at all. The belt didn't break. I put a new one on of course. But no issues with a broken belt.

My point there is, there'd be a noisy warning before the A/C compressor seizing causes the belt to break. That is a pretty strong belt.
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-E300d '99 350k
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Sold
-F250 '96 7.3
-Dodge Ram 12V
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-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.
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  #4  
Old 08-15-2008, 09:51 PM
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My TDI doesn't have a klima relay like device, neither does my mom's van or my sister's Pontiac (All of which are equipped with a serp belt, my sister's 3800 equipped Grand Prix actually uses the same belt as my SDL!). Not sayin it's a bad system, but IMHO it's a little over the top.

-Jason
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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
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  #5  
Old 08-15-2008, 10:25 PM
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My '85 came to me with a similar modification. The 617 engine has separate belts and no speed sensor on the compressor, of course. As soon as I understood what Klima was for and got a new one, I removed the mod.
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Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
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  #6  
Old 08-16-2008, 02:34 AM
compress ignite's Avatar
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"Over the Top"

COMPU 85,

The engineers in Stuttgart were most concerned with the serpentine belt's
ability to continue turning the water pump.Almost everything is designed to
default to being able to drive the automobile home.

We must remember the idea of hanging a compressor on one of their engines
,merely to "Comfort" the occupants,caused many sleepless nights and probably
near riot conditions in the engineering section.

The final straw on the camel's back,for Mercedes engineers,was the rumor that
someone in North America was inquiring about "Cup Holders".

And we wonder about what happened to QC on the Mercedes imported into
the U.S. ???
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  #7  
Old 08-16-2008, 09:33 AM
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Quote:
Originally Posted by compress ignite View Post
COMPU 85,

...
The final straw on the camel's back,for Mercedes engineers,was the rumor that
someone in North America was inquiring about "Cup Holders".

...

Yeah! What's up with that? My wife has become my cup holder since driving these things
__________________
-E300d '99 350k
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-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.
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  #8  
Old 08-16-2008, 02:37 PM
oso oso is offline
'87 300TD
 
Join Date: Oct 2007
Location: San Antonio, TX
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KLIMA relay

My "shade tree" mechanic "fixed" my problem of a/c compressor disengaging after a couple of minutes and not coming back on. He would not tell me what he did, but the air was cold and compressot was working. All the time! I looked around myself enticed by the "mystery" fix and found...a bridge under the socket! Now I understand...! Once I took the wires out, compressor is not engaging again.Where do I go now?
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  #9  
Old 08-16-2008, 06:36 PM
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Quote:
Originally Posted by oso View Post
My "shade tree" mechanic "fixed" my problem of a/c compressor disengaging after a couple of minutes and not coming back on. He would not tell me what he did, but the air was cold and compressot was working. All the time! I looked around myself enticed by the "mystery" fix and found...a bridge under the socket! Now I understand...! Once I took the wires out, compressor is not engaging again.Where do I go now?
Either to the dealer or to the search button of this forum.

I of course posted my fix in this thread. It works fine. The compressor comes on when the A/C button is pressed as long as there's enough freon in the system. But as mentioned if the compressor locks up the only protection to the engine are my ears and eyes listening for the belt squeeling as well as watching for lights (battery light etc) to come on. I really don't think it's going to be an issue. I'm willing to take the risk. But the proper way to fix it is with a new Klima relay (In my case and possibly other parts). There are several things to check through to fix the issue. Here they are... these are originally from a member named Saumil on this forum:

Testing proceedure for the CCU and Klima Relay and electronics for my 87 300d (also for the 300SDL, maybe others)

1. Turn Car Off
2. Pull Klima Relay Out
3. Put your multimeter on DC Volts setting
4. Connect the ground terminal of the meter (black color usually) to the battery's negative terminal
5. Connect the positive terminal of the meter to pin number 5 in the socket (Hopefully, you know which pin is 5)
6. You should get close to 12V, if not, the fuse is blown (#7 I think). Replace fuse. Put the Klima relay back in and check a/c again.
7. If the fuse is o.k. and the compressor clutch still does not run, then lets move on
8. Remove the Klima relay. Now connect the negative terminal of the meter to pin number 10 in the socket. (Hopefully you know which is pin 10). Put the positive terminal of the meter on the positive terminal of the battery.
9. Turn on the car and press one of the a/c switches on the push button unit.
10. You should get close to 12V when the a/c switch is on.
11. If you dont get close to 12V then there are one of two possibilities:
a. the push button unit is not sending the correct control signal
b. the pressure switch is not closed
For now, I am ignoring the trivial possibilities that wires or connectors may be broken. We can dive into these once we have some answers to the basic tests.
12. Turn the car off.
13. If you dont get the 12V, disconnect the two cables from the pressure sensor (should be at the drier), and jumper them.
14. Repeat steps 9 and 10.
15. If you still dont get the 12V, the push-button unit is not sending the signal.
16. Turn car off, dont keep the car running for a long time with the pressure switch cables jumpered.
17. If at step 14, you did get 12V, then the pressure switch is not closed
18. If the pressure switch is not closed there could be three possibilities:
a. refrigerant pressure is too low (lower than 2 bar)
b. refrigerant pressure is too high (higher than 30 bar)
c. the pressure switch is bad
you will need pressure gauges to seperate these possibilities.
16. If at step 11, if you did get 12V, then the push-button unit is sending the control signal and the pressure sensor is o.k. and we will move on.
17. If push-button unit is sending a signal and the pressure sensor is o.k. but the compressor clutch will still not run, then need to check the compressor clutch coil resistance.
18. Connect the positive terminal of the meter to pin number 7 in the socket and negative terminal of the meter to negative terminal of the battery.
19. Change the setting of the meter from volts to ohms.
20. You should get a low resistance about a few ohms.
21. If you don't get a low resistance, need one last test.
22. Get to the compressor and disconnect the connector for the compressor clutch coil (there is a speed sensor cable that connects to the compressor connector also, you have to trace the clutch wire to the compressor connector to pick the right pin on the connector).
23. Put one of meter's terminals on battery ground and the other terminal on the compressor's clutch coil pin (polarity does not matter).
24. You should get a low resistance, about a few ohms. If you do get the low resistance at the compressor then compressor clutch coil is o.k.
25. If you get low resistance in step 23 but do not get a low resistance in steps 18-19, then the cable from the Klima relay to the compressor is bad, replace it.
25. If you don't get a low resistance in step 23, then the compressor coil is open, normally this would require a new compressor.
26. If the compressor clutch coil is o.k. and the cable from the Klima relay to the compressor is o.k. then let us move on.
27. At this point, if the fuse is o.k., and the compressor coil's resistance and cable are o.k., then jumper pin number 5 and 7 in the socket.
28. Turn on the car and your compressor should come on.
29. Turn car off
29. If the compressor does not come on, there are two possibilities:
a. the fuse is blown
b. the compressor has an internal mechanical problem, is likely seized.
30. No matter whether it is 29a (shorted coil) or 29b (seized), compressor is bad, replace it.
31. If the compressor comes on at step 28, but does not come on when the Klima relay is put back in and the push button switches are on a/c, then the Klima relay is not producing the 12V signal at its pin 7 to drive the compressor.
32. If Klima relay is not driving the compressor at step 31, then there are five possibilities:
a. the temperature sensor is bad
b. faulty throttle cutout microswitch
c. bad compressor speed sensor
d. bad engine speed sensor
e. bad Klima relay
33. Put the meter back on voltmeter setting. Do this test with engine cooler than 105 deg-C, better when just cold.
34. Put the positive terminal of the meter on the positive terminal of the battery. Put the negative terminal of the meter in pin 12 of the socket.
35. If you get about 12V, then the temperature sensor is bad. I am not sure about the physical location of this sensor but on my 87 260E, it is a 3 pin sensor on the engine I think third from last from the windshield side. You can ask your parts vendor about it.
36. If the temperature sensor is bad, then disconnect the sensor cables, put the Klima relay back, and try you're a/c. If this was the only bad component, your compressor should start working. But again, don't keep running like this, replace the sensor as soon as you can. If disconnecting the temp sensor cable does not work, there is still another problem. Remove the Klima relay and move on.
37. Put the positive terminal of the meter on the positive terminal of the battery. Put the negative terminal of the meter in pin 4 of the socket.
38. If you get about 12V, then the throttle cut-off switch is bad. This switch is supposed to be open and only close when the throttle is wide open. I am not sure about the physical location of this switch but you can ask your parts vendor about it. Once again, if you can find this part, you can disconnect the wire, put the Klima relay back and check a/c. If it still does not come on, then there is some other problem and move on.
39. Change the meter setting to measure resistance.
40. Put the positive terminal of the meter on pin 9 of the socket. Put the negative terminal of the meter in pin 11 of the socket.
41. You should get about 350 – 450 ohms. If you don't get the low resistance but get very high resistance, either the compressor speed sensor is open circuit or the wire is broken somewhere. Do the same test as close as possible to the speed sensor (i.e. on the compressor connector) to rule out a broken wire. Replace sensor if it is bad.
41. If the resistance is o.k., then, jumper pins 5 and 7 on the socket.
42. Change the meter setting to ac volts.
43. Turn on the car.
42. You should get about 0.3V ac at idle of about 750 rpm. If you don't get the ac voltage, and the resistance was kind of o.k., replace the sensor.
43. Turn off the car.
43. To check engine speed signal, put the meter setting to ac volts
44. Connect one terminal of the meter to pin 1 of the socket and the other to pin 2 of the socket.
45. Turn the car on.
46. At idle of about 750 rpm, you should get a voltage greater than about 4V ac. And the voltage should increase with increase in RPM.
47. Stop the car
48. If you don't get the voltage, switch the meter to resistance setting and readout the resistance between pins 1 and 2 of the socket.
49. You should get about 2 Kohms. If you get a very high resistance, check the resistance closer to the sensor to rule out a cut in the cable. Otherwise replace the sensor. Ask the parts person about its location.
50. If in step 15, you determine that the push-button unit is not sending the control signal, replace the push-button unit.


But as you can see, I got tired of messing with this after getting it working once before to have more problems 6 months later and a REALLY hot ride to Oklahoma a couple weeks ago. So... NO more Klima Relay to protect. Just me. Hopefully my wife is as sensitive to noises and lights/gauges as I am.
__________________
-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.
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  #10  
Old 08-16-2008, 06:39 PM
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... After going through that checklist more than once or twice to keep the A/C going, I got tired of messing with it. After looking at that list you can see why!!

It was so long I had to delete some of my extra text to get it to fit in one post (10000 character limit)!!!
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-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.
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  #11  
Old 08-16-2008, 08:01 PM
oso oso is offline
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Love "to do "lists, especially when they are laid out so well. Off I go.....
Thank you.
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  #12  
Old 08-29-2008, 12:29 AM
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On my car, I pulled the Klima out, and took the case off of it. I saw there was a break in the circuitry on the circuit board. I soldered it shut, put the cover back on, and it worked. I suspect that many of the problems are the same with the Klima.
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  #13  
Old 08-29-2008, 01:06 AM
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Cruisin on Electric Ave.
 
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Location: La Conner, WA
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Hey, like I said... I don't think it's a bad system. I'm not going to remove it from my SDl. But I'm not going to retrofit it to my TDI either.


-Jason
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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.
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  #14  
Old 08-29-2008, 09:33 AM
777funk's Avatar
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Quote:
Originally Posted by amosfella View Post
On my car, I pulled the Klima out, and took the case off of it. I saw there was a break in the circuitry on the circuit board. I soldered it shut, put the cover back on, and it worked. I suspect that many of the problems are the same with the Klima.
I did the same before this fix. I think the relay itself was bad on this board as well as other oxidization of solder connections. I gave up on mine and did this instead. Works perfect now of course. And I'll be keeping an eye on things.
__________________
-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.
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  #15  
Old 08-29-2008, 11:19 AM
compress ignite's Avatar
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Thanks!

Excellent Resolution!

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