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  #1  
Old 06-29-2008, 09:42 AM
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A/C Question 1985300SD

I cannot get the compressor to engage. I ran a direct line from the battery and the compressor runs fine. I have bypassed the pressure switch but that did not help. Does anyone know of any shortcuts to find problem I am tempted to run a 12 volt switch to compressor,it is hot in S.C. Help
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Old 06-29-2008, 10:35 AM
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I don't know if the 1985 SD's A/C is the same as the D and TD, but there is a thread going on right now related to those that you should check out:
Possible causes of AC compressor not engaging
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  #3  
Old 06-29-2008, 01:07 PM
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Quote:
Originally Posted by jack avant View Post
I am tempted to run a 12 volt switch to compressor,it is hot in S.C. Help
No... bad idea. The various relays involved provide info to shut the compressor down not only when you have enough cool air, but also when there are other problems that could ruin your compressor (or even your engine) if it didn't disengage. Troubleshoot the problem or take it to someone who can. If you want to do it yourself, then jump in on the other thread - also good to see if you can get the wiring diagram for your system. If you don't have access to one, you can ask around here and someone can probably help you out with that.
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Old 06-29-2008, 01:20 PM
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Quote:
Originally Posted by jack avant View Post
Does anyone know of any shortcuts to find problem I am tempted to run a 12 volt switch to compressor,it is hot in S.C. Help
Why is everybody always looking for shortcuts?? Troubleshoot and fix the problem.
I'm just sayin'..........
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Old 06-29-2008, 01:51 PM
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You want to check out testing in search. My '84 just has a relay, but in '85, I believe they went to Klima. One guy here has a whole list of shortcut tests to figure it out. Wish I could remember who it is, but it was someone smart and creative.

Shortcuts are nothing more than a quicker path, found by trailblazers, and passed on to others. Think of the Oregon Trail, Panama Canal, etc. Nothing wrong with intelligent shortcuts.
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A/C Question 1985300SD-screenhunter_04-jun.-29-09.42-large-.jpg   A/C Question 1985300SD-screenhunter_05-jun.-29-09.44-large-.jpg  
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Old 06-29-2008, 03:04 PM
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Quote:
Originally Posted by jbaj007 View Post
You want to check out testing in search. My '84 just has a relay, but in '85, I believe they went to Klima. One guy here has a whole list of shortcut tests to figure it out. Wish I could remember who it is, but it was someone smart and creative.

Shortcuts are nothing more than a quicker path, found by trailblazers, and passed on to others. Think of the Oregon Trail, Panama Canal, etc. Nothing wrong with intelligent shortcuts.

Here's the entire set of tests to determine the issue when a Klima is present. Note that the vehicle is an '87.............the '85 is slightly different.

ac still not working after ac conversion 87 300SDL
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Old 06-29-2008, 08:51 PM
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I believe on the '85 there's a switch on top of the camshaft cover which opens the compressor circuit during full throttle.
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  #8  
Old 06-29-2008, 09:32 PM
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Kilma switch

I read a link where you could short out jumper #5 and 7. I did that and A/C started working. Does that mean that kilma relay is bad or what. This was what I was asking for when I asked for a shortcut. My 1984sd does not have a Kilma. Thanks for the input.
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Old 06-29-2008, 11:05 PM
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Quote:
Originally Posted by jack avant View Post
I read a link where you could short out jumper #5 and 7. I did that and A/C started working. Does that mean that kilma relay is bad or what. This was what I was asking for when I asked for a shortcut. My 1984sd does not have a Kilma. Thanks for the input.
As far as I understand it, jumping pin #5 to #7 is simply putting 12 volts to the compressor. Again, you could do it if you want, but it's not really solving the problem. Either the Klima is bad or something feeding info to the Klima is not functioning properly - or something else is wrong (low refrigerant) and the sensors and relays are fine and doing what they are supposed to be doing. Now, that might not help you much, but you'll have to dig around to find out. Try jumping various sensors (i.e. low pressure cut-out, etc) to see what you get - the more info you have the better off you will be. Have a look at the Klima first and try to find a wiring diagram.

You might find something useful here:

Quote:
Originally Posted by tankowner View Post
Once the Klima relay is out, take a look at the pins, notice that each one is labeled. The following posts have info about the function of each of the pins. The Klima relays being referred to in these posts are not exactly the same as the Klima/Kickdown relay in the 95 E300D, but as you will see they are pretty close. Between the wiring diagram and this info you will be better off in trying to locate your problem.

See post #5 here:
http://www.peachparts.com/shopforum/showthread.php?t=95748

And post #21 here:
http://www.peachparts.com/shopforum/showthread.php?t=102024&page=2
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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  #10  
Old 07-01-2008, 09:07 AM
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Kilma relay

First of all I would like to thank all for the information provided. The pressure switch is good. I am in the process of checking out other things. I jumpered #5 and #7 pins on kilma and the compressor works. I will troubleshoot and use the process of elemination. I had no idea that the kilma looked at so many functions. My 1984300sd does not have one on it.
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