Just got some help to install my new AC compressor, before we installed it I thought to power the clutch and turn it over by hand. Could barely turn it. Tried the old unit and it spun easily. Going to return it, I have to assume it's garbage.

Can anyone suggest a good brand that might be available at a local parts store please?

Edit i should note that I did this with the lines uncapped, so it is not likely a vacuum/pressure lock. I cant imagine that it is normal for a compressor to turn that hard, I am sure it would burn up a belt

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Wondering if maybe the oil all flowed into the compression chamber for lack of a better word since I stored the compressor pulley down. Tried turning it on the side and will let it drain for a bit. Worth a try.

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

This is perfectly normal of a new R4 compressor. They are nearly impossible to turn over by hand and most brands will include this information in the box that the compressor came in. This is why it is absolutely imperative to follow the correct installation, oil quantity, and four minute idle break-in period (Service Information - S83/26 25.07.1979). If you can turn it over by hand when out of the box, the compressor will NOT last long.

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1985 300TD - "Panzer Wagen" - undergoing full restoration (resto - mod)
2014 GLK250 Bluetec - Wife's car

Mercedes-Benz Master Certified Technician.

http://www.flickr.com/photos/joshuajeeper/

Great news! Thanks!

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild

Sure thing!

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1985 300TD - "Panzer Wagen" - undergoing full restoration (resto - mod)
2014 GLK250 Bluetec - Wife's car

Mercedes-Benz Master Certified Technician.

http://www.flickr.com/photos/joshuajeeper/

Do you mean you tried to turn it with the clutch ON? If so, it is then connected to the belt so won't turn unless the crankshaft turns. Regardless, if already installed might as well just try running it since worse you risk is a burnt belt.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I tried turning it on the bench with the clutch on

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'85 300D - federal spec, built in late 84. 85 300D Complete AC System Rebuild