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  #1  
Old 06-23-2006, 04:14 PM
Hit Man X's Avatar
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Thumbs up SDL + A/C = no go

Well I checked it finally today, it's full of R12... and no leaks. Bad side, doesn't turn on.

Klima relay is new, yet I have a used PBU in there. Also, could the switch on the dryer be bad or the speed sensor on the compressor?
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'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

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  #2  
Old 06-23-2006, 04:35 PM
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Angry SDL A/C problems

I know what you are going through. My 86 SDL (209,000 miles) and I have had so many A/C problems that it is not funny any more. My last one was solved as follows:
Sitting on top of the compressor, there are a series of electrical connections. These are hard to see and they collect lots of grime. After checking many of the usual problems, (Fuses, Relays etc.) we cleaned these with some simple green and now (for now) all is working. There are so many causes for the A/C not to work, MB should be spanked for this system. Also be sure to look at No.5 fuse and change to at least the blue fuse as well. Hope this helps.
Ron
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  #3  
Old 06-23-2006, 04:38 PM
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So you put the guages on both sides with the engine and compressor not running ?
What pressure reading (s) did you get ?
My books only cover the 123 ... the klima and that speed sensor are off my radar.
You can check that switch with either an ohm meter or 12 volt light tester.
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  #4  
Old 06-23-2006, 04:48 PM
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I have two vehicles with A/C... one is trapped in the garage, the other is out of town.

I had 90psi on the low side with the compressor off and motor on, I didn't bother hooking the high side as it wouldn't kick on.

Is there a way to jump the compressor to turn it on?
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I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
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  #5  
Old 06-23-2006, 06:26 PM
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More fuel for the fire...

Apparently that speed sensor is related to the tach operation? My tach doesn't work currently as the cluster needs to be rebuilt. Anyknow know if the A/C wiring runs through the cluster too?

When first flipping on the PBU on installing the Klima relay, the compressor will turn a few times then flip off too. Seems to be pointing more toward that speed sensor maybe?
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #6  
Old 06-23-2006, 06:51 PM
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Quote:
Originally Posted by Hit Man X
More fuel for the fire...

Apparently that speed sensor is related to the tach operation? My tach doesn't work currently as the cluster needs to be rebuilt. Anyknow know if the A/C wiring runs through the cluster too?
AC won't work w/out the tach. Such an over engineered mouse trap!! My '85 also uses the Klima, and must have the tach. Take a look at this link. It shows how my Klima is bypassed, as my tach has never worked.
It's 2 days, and I still have cold AC......

Klima Relay issue


BTW, that SD was very very clean! Not as clean as the white one of a few weeks ago, but a well above average specimen......
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'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
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Last edited by JimmyL; 06-23-2006 at 06:57 PM.
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  #7  
Old 06-23-2006, 08:03 PM
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So the paint was good? Well damn, someone else PM'd me about it...

Damn the tach!
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #8  
Old 06-23-2006, 08:22 PM
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Quote:
Originally Posted by Hit Man X
So the paint was good? Well damn, someone else PM'd me about it...

Damn the tach!
Said motor problems on the window sticker. Dent in the hood as if a pulley let loose at some time. It had also been repainted. I found primer overspray on a door jam.
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  #9  
Old 06-23-2006, 09:46 PM
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Quote:
Originally Posted by Whiskeydan
Said motor problems on the window sticker. Dent in the hood as if a pulley let loose at some time. It had also been repainted. I found primer overspray on a door jam.


They also said that with my black 745i, just needed valves adjusted and a hose replaced.

I hate crappy repaint.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #10  
Old 06-23-2006, 11:44 PM
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It was very presentable, and the interior wasn't bad at all. One of the hood dents did come from underneath.
So, WhiskeyDan, what time were you out there? What were you driving?
When I left there was a 380SE parked out front.....
BTW, I didn't see any hay out there.......
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'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John
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  #11  
Old 06-24-2006, 03:09 AM
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Remove the Klima and turn on the AC at the PBU. Check for +12V at pin 10. If that checks, jump pins 7 and 10 to send power directly to the compressor. If that doesn't work, check the compressor clutch gap and the wiring to the compressor.

AFAIK the pressure switch at the dryer is upstream of the Klima. Doesn't hurt to jump the brown connectors to make sure the pressure switch isn't the problem.

The tach and Klima take an engine rpm signal from the flywheel sensor below the oil filter. It's a parallel feed - AC will work with no tach and tach will work with no Klima.

EDIT - Get a second opinion on this because my memory is sketchy. It could be that the PBU sends a ground signal to the Klima to engage the compressor. If so then mup pins 5 and 10 to engage the compressor.

Sixto

Last edited by sixto; 06-24-2006 at 03:25 AM.
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  #12  
Old 06-24-2006, 03:15 AM
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Well it blips on then off quickly after you first drop it in. I'll get to it next week, I'm frustrated.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #13  
Old 06-24-2006, 03:22 AM
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Sounds like an rpm problem. Either the compressor rpm signal is bad or the engine rpm signal is bad. Check AC voltage at Klima pin 2 for engine rpm. I forget the value I got but it should increase linearly with rpm. You can do the same across pins 9 and 11 for compressor rpm if you can catch a measurement before the compressor cuts out. If engine rpm checks out then a bad compressor rpm sensor is high on the list.

How do you know the tach is bad?

Sixto
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  #14  
Old 06-24-2006, 03:24 AM
Hit Man X's Avatar
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Thumbs up

Quote:
Originally Posted by sixto
Sounds like an rpm problem. Either the compressor rpm signal is bad or the engine rpm signal is bad. Check AC voltage at Klima pin 2 for engine rpm. I forget the value I got but it should increase linearly with rpm. You can do the same across pins 9 and 11 for compressor rpm if you can catch a measurement before the compressor cuts out. If engine rpm checks out then a bad compressor rpm sensor is high on the list.

How do you know the tach is bad?

Sixto


The PC board in the cluster is cracked! One light only works due to this also.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 244k
'87 300SDL 251k
'90 300SEL 325k
'91 560SEL 189k

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
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  #15  
Old 06-24-2006, 03:26 AM
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I suppose a ground or crossed engine rpm wire at the tach PCB could affect the engine rpm signal to the Klima.

Sixto
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