Just bought my first Mercedes from my boss (81 300SD), and when I asked him if it had air conditioning he told me no. After some investigation, I found the A/C compressor installed, belt removed, and wires cut. To make it even stranger, the pulley doesn't even seem to line up to the empty pulley on the motor. I'd like to get the A/C working. Can anyone tell me whether I can install a new pulley and belt, re-connect the wires and try it or am I better off buying a new compressor for $500. I am pretty new to this air conditioning thing and I don't fully understand how it works. Any help would be great! thank you!!!

 

Usually no belt, cut wires (don't understand why someone would cut the wires.), means a compressor has locked up and had to cut the belt so the motor would run without burning the old compressor, sending metal shards into A/C units ($4,000grand repair on a SEC.) And possible other engine damage.
The pullies is strange too unless the compressor is not installed straight.

One quick tell-tell sign of a locked up A/C compressor is try moving the compressor clutch/pulley (The part that the belt connects to the compressor.) It should be able to spin freely (assuming the A/C is off) meaning it should be disengaged. If it's stuck, it might be and more than likely locked up.

The easiest way to get to the bottom of this is ask your boss about it. Ask him what happened to the compressor. He should know if there was a new compressor installed recently. If not, then might as well buy a new one.

(Note: Some people opt for used ones, but this is very risky if you are not mechanically inclined and or don't know too much about refrigeration and the what to look for on an properly operating A/C compressor and other components.

 

The Compressor was disconnected before my boss bought the vehicle and he hasn't bothered to look in to it. I can spin the pulley freely, but I think (and this is just a guess) that the wires on the unit control the clutch to engage the compressor. So really the only thing to do is hook up the wires, turn on the A/C, and then see if the compressor pulley is still moving freely?!? And wouldn't I need to have refrigerant in order for the compressor to produce a resistance to my spinning the pulley?!? I found a new compressor for $350 in California, but I don't want to buy it and install it without being sure that the compressor failing was the reason for the previous owner to disconnect it. Is there anything else I can check?

 

a place for dirt cheep parts
www.getcoolparts.com they give free advice

 

well 99.9% of the people I heard about wouldn't just disconnect a good compressor for no reason.

Then the questin is, is there refrigerant in it. And if there is has it ever been converted? In a way, you better off taking it somewhere and get a A/C mechanic to look at it and test it.

And then again a new compressor for $350 is nice.

My gut feeling is to just replace it. A new one can't hurt. But get it checked out.

 

I found a rebuilt compressor here locally for $236 Canadian... For that price I will take my chances and replace it. Thanks for all your help!