A little bit of simple investigation may reduce your worries.

Look up your truck at rockauto.com, a FTE sponsor. Look at the pictures of compressors, and clutch.

Look at the pic of the compressor without a clutch. It has an exposed "snout" at the front. The pulley with its bearing rides on the snout. All belt tension bears on the snout, not on the compressor shaft. With no DC power to the coil, the pulley just turns on the bearing that is over the snout, nothing else happens.

Effectively fitting inside the pulley from the back is the electromagnetic coil. When energized by 12 v DC, it magnetizes the pulley. The front perimeter face of the pulley is machined flat, and will be like the flywheel in a manual transmission.

The "hub" consists of a steel plate (the clutch plate) and a hub that attaches to the compressor shaft, and a rubber and metal retraction mechanism between the two, whose purpose is to keep an air gap between plate and pulley face when the coil is not energized.

With the A/C is OFF, the pulley will turn, the clutch plate on the front should NOT turn, and therefore the compressor shaft will not turn.

*** First check*** - With engine running, A/C OFF or cycling, but while the compressor should be OFF, the clutch plate should never touch the pulley. If it does, even a little bit, it will make a "zing" sound. The more it touches, the more noise it will make, and if it touches enough, the plate will spin sporadically, and the compressor shaft will turn some. If this happens, either the air gap is too tight, or much more likely, the rubber in the retraction area is tired.
I had a 302 car do this once, when I pulled it apart, the clutch plate retraction was about zero, the rubber was really shot as seen from the back when pulled off.

***Second test**** - With engine running and A/C ON, the coil is energized, which magnetizes the pulley, the magnetized pully attracts the clutch plate, the clutch plate SHOULD solidly contact the pulley, and the hub should turn, turning the compressor shaft at the same rate as the pulley is rotating. IF the clutch plate is slipping some, it can make a noise, you will see the clutch plate jerk some, instead of turning fast and smooth when the coil is energized.

A slipping clutch plate can be caused by faces worn down so far that the air gap has increased, lessening the magnetic field, or too big of a gap initially (less likely), corrosion on pulley face or back of clutch plate so not contacting well, or low current to the coil due to poor electrical connection, etc.

Getting in there and seeing it will help a lot. Watch out for rotating parts and belt! May need flashlight and mirror to see it well.

You can also take the belt off, and spin the pulley clockwise by hand to do a rough check of the bearing.

Other thoughts... don't replace what doesn't need fixing. Original FS10 compressor was made by Denso, I would only use a Denso for compressor replacement, if it ever needs it. I would not touch some uh, other brands.
Even though you have 198,000 miles, your compressor has nowhere near the operating hours on it that we get here in Texas on vehicles with a lot less mileage. Our car A/C season can be the whole year in some areas. For me its 9-10 months possible. Strong sun.

 

The rattling noise is a separated hub clutch plate.

Please, do yourself and everyone else a favor and go look at it instead of endlessly talking about it.

 

I've been to the RockAuto site from the beginning and postulated these many questions. One question. What are the little spacer washers in the pictures of the clutch assembly for and how are they installed or adjusted? I too noticed that the Motorcraft comp. looked exactly like the Denso one and figured they were the same. Your detailed commentary is what I've been waiting to hear and now explains a great deal. So if I install a new clutch assembly, I should be good to go given the spacer washer issue I need an answer on.

 

The spacers/shims are what set the clutch gap during reassembly.

 

All right, what clutch assembly should I go with: "Four Seasons", "Murry", and "Factory Air" seem to be the same part yet a different design from the OE Motorcraft triagular clutch face design. I tend to go with Motorcraft mostly but no one has them in-stock up here. The only way I can get a Motorcraft is to order one, pay shipping and core charge. The aforementioned brands are available in NEW, not reman. Opinions please and again, thanks for your help.

 

Motorcraft for the clutch parts.

 

"Four Seasons" sells parts under at least 4 different names. You listed 3 of them, the 4th, IIRC, is Everco. I used their clutch assembly for an FS-6 compressor without problems, it's a pretty low-tech part.

Availability of A/C parts is a problem, particularly for older vehicles. Its hard to get away from 4 seasons and all their sales names. Sometimes you just don't have a choice. Almost all vehicular A/C components are made in China these days. But the Denso FS-10 compressor is made in Mexico by Denso. I bought one from Rockauto a few months ago on another project.

To pull the clutch assembly, you will have to figure out how to hold the clutch while you break the shaft bolt free. Parts stores usually have a loaner tool for this, a clutch plate holder. You can probably rig something up, there are usually some holes in the plate, that you could stick some screws through a bigger scrap piece of metal and then into those holes. And hold onto the big piece to hold the clutch from turning while breaking the bolt free.

1997 shop manual says clutch plate to pulley gap (measuring in 3 places around the periphery) should be .018 to .033 inches. Just put a shim on the shaft before the clutch goes on.
Torque shaft bolt to 9 - 10 ft. lbs.
The selection of shims is trial and error, so you will probably be putting it on and taking it off. Measuring the gap, and measuring the remaining shims individually and a little simple math will get you to a proper shim solution pretty fast.

Hey SHO, can you recommend a drop-in replacement for R-12 that costs less than $1 a pound and can be used as a furniture polish too? (just kidding, SHO)

 

Yes, I saw that Everco on the AutoZone site. They're new to our area. What really sucks is there used to be soooo many private auto parts stores up here, now there's just Auto Value, O'Reilys, Advanced, NAPA and a Carquest. All chain stores. A part could always be had in the good old days. Now so much has to be ordered and core charged. I've been buying quite a bit from Rock-Auto. It's a great resource to compare parts also. Of coarse Ford used to carry every little part in-stock, now they have to order most everything. There are 2 on-line Ford sites that sell at quite a discount: Silverstar & Ford parts Discount Outlet. Also "Vintage Parts" where I located a brand new manual floor shift 4x4 shift mechanism/linkage.

Back to the clutch. So it could take more than one spacer? I imagine setting it to the lower side of that spec will give longer service, say .020ish. OE Manual also says the magnet must be pulled off and pressed back on with an 8 X 1.25 mm bolt and special adapters/pullers. I suppose I can improvise given there is enough room? I'll shoot for the Motorcraft YBR111RM if I can find it with out too much shipping, core, and tax in the $130.00 ball park.

Ya know, i still have an NOS can of R-12 in the garage.

 

Don't know about the furniture polish, but, if you like living way off on the wild side, you can always use propane. The advantage of that is that you can always grill steaks if you have a leak, at least until the fire department shows up!


Way back when I was dealing with this same issue on my 97, I picked up a hub from the local AutoZone. It didn't fit! Unfortunately, I'd lost the receipt do I was out the $35 I'd paid for it. That is why I now only recommend Motorcraft for hub and pulley replacements

Removal of the hub is easy. If it does engage when it's supposed to, all you need to do is switch the ignition to RUN without starting the engine and turn on one of the AC modes. The clutch will pull in. Use a wrench (8 or 10 mm, I forget) to loosen the bolt and remove it. Turn the ignition switch back off and then remove the hub taking care not to loose any shims behind the hub.

Once the hub is off, you can check to see if the pulley bearing is bad (remove the serpentine belt, of course).

Seriously, you've wasted more time agonizing over this than the 5 or 10 minutes it would take to actually perform this simple task. Once you take it apart, it's easy to see what you actually need to do to repair the problem (instead of just talking about it).

 

I just ordered the Motorcraft YRB111RM AC clutch off ebay for $107.00 no tax, free shipping, no core charge, and its only 311 mile away. Nobody else had it for less than $200 Total or even in-stock w/o ordering it. Is it really necessary to replace the electro magnet if I can't get it off, does that part really wear out to. Sorry for all the questions.

Thanks again!

 

Did you ever actually LOOK AT IT as recommended numerous times?