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79 450SL Compressor Replacement

8K views 15 replies 5 participants last post by  krigsmakten 
#1 ·
Another AC question (yeah, it is about 100 in Houston today!).

Just got the car back from a reputable service center. They have informed me that the compressor is shot. They evacuated and charged the system (R12) and there were no leaks. The compressor came on, but the pressure was the same on the low and high sides. So, I think they may be right. How difficult is it to replace the compressor? Is it DIY? I did the one on my 98 ML320 and it was a piece of cake. Easy access, etc. Does anyone have a procedure for this work? I will likely go with a remanufactured unit.

A little history - my wife got the car from her father several years ago and we have just been storing it until this year. The AC has never provided cold air and until now, I haven't messed with it.

Thanks.
 
#6 ·
On the compressor note - has anyone tinkered with "upgrading" the A/C system?

I'm not talking about destroying it by switching away from R12 - just checking if anything can be done to increase cold air flow into the cabin.

I'm in Atlanta, and even with good R12 pressure readings in the system, I would still like to get more cold air...

Air compressor, fan, evaporator, condenser, blower... where is the bottle neck?

Thomas
 
#8 ·
Well, it sure as hell ain't the compressor, at least while MB was installing that A6. Those will pump enough refrigerant to frost the glass on a Vista Cruiser for cryin' out loud. Got to be the evaporator/condensor sizing, and there's not a whole lot more room to upsize there.
 
#9 ·
An SL - with the 5.0 aluminum engine and the "new" style rear end from a 1978 450SLC 5.0. Period correct pieces - I think I have read about at least one other 450SL being retrofitted with the 5.0 engine - done in Germany back in the day. AMG probably did this too - what didn't they do?

Thomas
 
#14 ·
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Blower should work at all speeds in all modes.
There's only HI and LO in my '78 for the A/C - and HI does not seem to spin as fast as it does in DEFROST mode. HI spins a good deal faster than LO, but it's not exactly the blast of air I get in my E550. Unfair comparison of course, but I'm looking to make it a bit more powerful. Perhaps a blower rebuild will do that? - has anyone done one and noticed a before/after speed change?
 
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