One more SDL AC puzzle!! - PeachParts Mercedes-Benz Forum

avendlerdp · #1 10-03-2006, 01:31 AM

I did many a search and learned a lot. Still need more help. 1986 SDL. AC compressor will not come on. All CCU stuff seems to work but I have yet to test the #10 for ground when the AC is on and low pressuse switch is bridged. I'll do that in the morning.

Some questions:

1. What pins on the KLIMA do I jump to turn on the compressor?
2. Is it normal for there to be an empty space in the relay area of the fuse block? It has no plug or anything, just a hole.
3. I have a good used KLIMA relay in the car now but it's from a gasser W126 and I am not sure if it will work with my SDL.
4. Where can I get the specs for all the KLIMA pins so I can see if anything else is bad?

For starters though, I just want to bypass the KLIMA so my AC guy can finish charging the system.

Please help, and thanks in advance.

-Alex

JimmyL · #2 10-03-2006, 01:37 AM

HitMan, this ringing a bell...........

Hit Man X · #3 10-03-2006, 06:27 AM

Is it ever!

Read this - http://mb.braingears.com/126_DISC1/program/Climate/1986.pdf

1. Can't recall, 5+7 rings a bell but dont until you confirm

2. I think I have a few empty holes too

3. Klima is specific for SDL. Rarely go bad.

4. See above link

You can get it to run no problem at idle to charge the system. Mine seems to SLIP as RPMs rise.

New Gatorback belt, new tensioner, new idler pulley. I'm concerned if my alternator is crap or not (not enough amperage to keep clutch locked) or the clutch itself is going.

When I jump the compressor to stay on, it's smooth and quiet. So the guts itself are fine. My PBU is okay too, proper ground at Pin 10.

Also within that PDF, it will show how to test the speed sensor. I need to do that also to verify it's not the issue. It's a cheap part too, about $60.

avendlerdp · #4 10-03-2006, 02:15 PM

Thanks for the help. I lke that website but for some reason i can't get any other PDF's it offers. All are broken links.

OK so here is the latest. I performed the tests in the order that they are outlined in the PDF you helped me get. The #10 pin goes to ground as it should when the CCU tells it to and not when on "ECON". There is power from the #5 as well. Here's the rub: when I bridge the #5 and #7 still no compressor. It looks like the compressor clutch is done. None of the 3 pins on the plug on top if the compressor continue to ground. Looks like a new compressor will fix this part of the issue. I tested the plug going into the compressor and one gets batt. voltage with the 5 and 7 bridged. Here's the next rub: If I put back in the Klima and turn on the AC I get no voltage to the compressor. It looks like I have two things wrong here. My low pressure switch works fine and there is enough in the system so it's on.

There is another un-used pressure switch on the dryer. Normal?

Last question, how does the compressor start up if the speed sensor tells it not to if it does not match engine speed? Is there a "start up" circuit in the KLIMA?

Thanks,

-Alex

Hit Man X · #5 10-03-2006, 02:29 PM

Ya have the aux fan switch (red) and the pressure switch (black) on the dryer.

You can turn the clutch by hand, just reach there and see if it's seized/dragging. If it's not seized, that's good. Still doesn't help like in my case.

The SS tells it not to run, how? I do not know. Within the Kilma, the best info at hand I've seen thus far is the PDF you have. Did you test your Speed Sensor per those directions?

avendlerdp · #6 10-03-2006, 04:18 PM

Belive it or not there are 3 switches on the dryer. Two are in use and one just sits there unplugged.

Anyhow, I think there is no way to test the speed switch without running the compressor. New compressor is on the way.

-Alex

Brian Carlton · #7 10-03-2006, 09:20 PM

Quote:

Originally Posted by avendlerdp

Here's the next rub: If I put back in the Klima and turn on the AC I get no voltage to the compressor. It looks like I have two things wrong here. My low pressure switch works fine and there is enough in the system so it's on.

There is another un-used pressure switch on the dryer. Normal?

Last question, how does the compressor start up if the speed sensor tells it not to if it does not match engine speed? Is there a "start up" circuit in the KLIMA?

If the CCU is properly grounding socket #10, the issue is either the Klima itself, or one of the speed sensors that the Klima uses to verify that the compressor is rotating. There are specific checks that you can perform to verify that the speed signal from the tach and from the compressor are correct. If they are correct, and the Klima won't engage the compressor, the Klima itself is the culprit But, a lot of folks have replaced the Klima, only to find that the problem remains. So, the tests must be done carefully. I'm not at home, so I can't provide them here, but, they are on Braingears.

I'm not aware of any unused pressure switches on the dryer.

That's actually an excellent question, and, one for which I have no immediate answer. The Klima can't get a speed reference, AFAIK, without the clutch engaged. But, the clutch can't engage unless the Klima gets the speed reference. Clearly a conundrum. I'm sure there must be a timing sequence in the Klima to allow the clutch to engage for a specific time before the Klima drops the compressor. The testing for the speed reference involves manually closing the clutch via pins 5 and 7, so, you'll need a functioning clutch before we proceed any further with testing of the Klima and it's associated sensors.

Hit Man X · #8 10-04-2006, 12:48 AM

Slow down speed racer, if you need only the clutch you can order only the clutch. No need to drop a grip for a new compressor.

Did you check and see if the clutch is seized? You can also only replace the speed sensor.

If you're planning to open the system, go ahead and order some o-rings, dryer, aux fan switch, pressure switch, and I'd do an expansion valve too while you have it apart.

avendlerdp · #9 10-04-2006, 09:59 AM

Hit Man-

Thanks for the tip on the clutch. Do you know where I can get one? Out host here seems to not have it. Also I am finding whole rebuilt compressors for around $300 so it's not too bad. This is assuming a rebuilt it going to be any good. Either way I have to go out of town for a while so I'll pick this up when I get back.

Thanks for all the help everyone.

-Alex

Hit Man X · #10 10-04-2006, 10:03 AM

Yeah, PM me.

Lots of mixed reviews on remans. I'd go new.

avendlerdp · #11 10-04-2006, 10:10 AM

It seems like the compressor is fine but I'll know for sure once i do the clutch. Can the clutch be changed without pullung the compressor and discharging the system?

Hit Man X · #12 10-04-2006, 10:21 AM

Without pulling? Yes. Without discharge, I'm pretty sure. Don't know on the speed sensor or not.