A/C compressor clutch replacement, do i need to replace pully to?

Hey guys, i've been trying to identify a few engine bay noises. I've found one of them is the A/C compressor clutch. The clutch is not fully disengaging when off, causing it to catch every once in a while. It makes kind of a 'chitter chitter' noise.

The clutch engages fine and the coil gets 12v the coil also measures 4ohms so i know its good. When the system is totally off and the wires from the compressor are removed it is engaging lightly causing it to spin just 1/8th turn over and over and over.. There is red-ish clutch dust all over the unit and surrounding area.

My question is..

I have 2 other a/c compressors in the garage which where pulled working. I plan to just put one of those clutches on it, and make sure the air gap is correct. Do I also need to replace the pulley? I ask because the clutch does engage against a plate on the pulley.. Is the red dust from the clutch or the surface of the pulley that the clutch is engaging against?

The other pulleys are v belt driven, so i'd have to go buy one  

I wonder if one of the clutch arms is broken. If not, I`d have a hard look at the bearing.

buickwagon wrote:

I wonder if one of the clutch arms is broken. If not, I`d have a hard look at the bearing.

Curious, how do the bearings come into play? I took the belt off and physically tried to wiggle the pulley around, it is very firm. The 'chitter' noise is directly related to the clutch only partially engaging. It is my guess that the air gap is not correct between the clutch and the pulley causing it to catch just enough to engage or the spring. I just dont know if i should replace the surface the clutch engages against or if I can get away with just cleaning it up and changing the clutch and giving it the correct air gap. i beileve its .003

im praying its not the bearings, i really dont want this system to be cracked open its original r12 and blows cubes.

The gap is supposed to be more like 0.015". About the width of a folded business card.

The question is "how did the gap get too narrow? Periodically." A cracked arm might explain it. A worn bearing might be enough. Or possibly corrosion growth (which would also explain the red dust).

buickwagon wrote:

The gap is supposed to be more like 0.015". About the width of a folded business card.

The question is "how did the gap get too narrow? Periodically." A cracked arm might explain it. A worn bearing might be enough. Or possibly corrosion growth (which would also explain the red dust).

yeah i meant .030(fat fingers) i think its between .025 and .035 at least that is the source i have, https://www.youtube.com/watch?v=URqFd3KkSRY very informative video.

The swap is easy enough so ill try the clutch first and cross my fingers.. I didn't have a feeler gauge when looking at it last night, but i cant get my fingernail in the gap, definitely not a business card.