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1983 380SL
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26 Posts
Discussion Starter · #1 ·
Im looking to get some ac going in my new to me 380 and am looking for tips to check and see if the compressor is good. The system has been changed over to R134 at some point. When I turn on the ac system the motor acts like there a load put on it but the clutch on the compressor doesn’t spin. I disconnected the 2 connections at the dryer and jumped them with a wire both with the key on and running, nothing happened. I also,put a test light on each of those dryer connections, didn’t show any power. Any other tests? Pictured are the connectors I jumped.
Automotive tire Gas Auto part Electric blue Valve
 

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1980 450 SL
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797 Posts
If it puts a load on the engine but doesn't spin the compressor it sounds like the compressor may need to be replaced. The clutch may start smoking if you leave it on.
 

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1973 MB 350 SL Euro 116 engine
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287 Posts
With the key on, but the engine stopped, do you hear a click from the compressor clutch when you select A/C?
Can you manually turn the inner section of the hub on the front of the compressor (engine shut off of course)? It's the inner flat ring that's ~3" in diameter and on the very front of the clutch, it should turn smoothly with some resistance, no gritty or lumpy parts.
 

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1980 450 SL
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797 Posts
About what I figured!

shouldn't I get power out of one of those 2 connectors with my test light though?
If it's connected and closed there would be no power drop across the 2 wires. Need to check it to ground. What matters is the voltage at the clutch. There is a chain of events down stream to check.
 

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1983 380SL
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26 Posts
Discussion Starter · #6 ·
With the key on, but the engine stopped, do you hear a click from the compressor clutch when you select A/C?
Can you manually turn the inner section of the hub on the front of the compressor (engine shut off of course)? It's the inner flat ring that's ~3" in diameter and on the very front of the clutch, it should turn smoothly with some resistance, no gritty or lumpy parts.
the clutch does turn with a little resistance.
 

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1983 380SL
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26 Posts
Discussion Starter · #7 ·
Anything else that should be replaced with the compressor? I’ve replaced the dryer and orifice tube filter on my old bronco when I got it’s system going. Found this kit on Parts Geek.

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1983 300SD/1982 380SL
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36 Posts
This looks fairly complete. Has expansion valve no orifice is used. Check the condition of your hoses.
I just replaced my 1982 380SL A/C compressor. It was a Nissens brand, significantly lighter that the old A6. I replaced the dryer and switches and flush the r-12 oil out of the whole system. My only issue right now is the AUX fan wont come on when the a/c is under load. So, since the temperature switch that I replaced is either faulty, or i have another issue. any ideas?
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
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13,872 Posts
About what I figured!

shouldn't I get power out of one of those 2 connectors with my test light though?
Yes but there are two switches. 1 is for the aux fan and 1 is for the compressor. Both should be on the RD. Those wires look like they were sliced in somewhere. Both solid color orange with auto part store female spade connectors.
 

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1983 380SL
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26 Posts
Discussion Starter · #12 ·
roncall, never noticed the wires, will look into that.

still waiting on the relay I ordered to come in so I can see if that is the issue.
 
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