Just removed the dead GM style compressor and installed the "direct fit" Four Seasons # 58096. All parts from RockAuto.
Thought I would share some points that came up for anyone else considering this work.
The new unit (not a rebuild) is Aluminium and weighs easily 1/2 of the original iron one. Don't ask me the weights, but lifting the old one over the wing, without help, was "challenging".

A) The original bolts used to attach the new comp. will not fit and will need to be replaced by new ones with a different thread style. Originals are a fine thread and the new comp. uses a coarse thread. Probably as it's housing is Aluminium and the original is steel/iron. Took the new comp. and the original mounting bolts to the local hardware store and picked up the new hardware.

B) So side by side on the bench all the back ports are blanked off on the new one. On the original unit I removed the cir-clip holding in the temp protection switch and removed the switch. First item to note is that the new one from Four Seasons #35961 is not the same as the old one. In fact the old one will not physically fit into the new compressor as the comp. housings are different. New switch installation instructions (supplied) says the new replacement switches have two leads and the old ones have just one. Says to attach one switch lead to the original switch wire on the car and the second to a suitable ground. Use either lead it says.

C) There is some kind of "safety valve" on the old unit and what appears to be a blanking plug on the new compressor. I removed the original one and the blanking plug on the new comp. only to discover that the plug is in fact a "safety valve" in miniature. So I left the "plug" in the new comp.

D) Dropped in the new comp. and all mounts and connections lined up. EXCEPT for one.

E) The belt tensioner does line up correctly but due to the re-designed clutch on the new comp. it fouls the clutch. The original adjuster needed to be modified by cutting the threaded rod where it attached to the engine block and welding it back on to provide a "jog" in the rod. By not using one of the adjuster spacers, the unit then lines up perfectly. The picture will explain it all. Thank goodness I have a neighbor with an arc welder. 15 minute to cut and re-weld the adjuster.

Note (untidy) "jog" in adjuster rod and 1/2" spacer removed

Note how adjuster fouls on new comp. clutch bolts.


F) The forward mounting bracket on the fuel cooler does not line up (perhaps it never did) so a small steel bracket was bent up to secure it properly.

And that's it for the install. Now on to the Dryer (URO Parts #CAC 1881)and expansion valve (Four Seasons #38872). A separate thread on the expansion valve to follow. Dryer appears to be a simple fit (but who knows!).

Hope this can be helpful.
Ian

 

and rock auto calls that a "direct fit"?

 

That's what I was told! PITA.
In fact, the Adjuster fix was a piece of cake.

 

you could have saved all that hassle with retro air's redesigned Harrison compressor:

https://retroair.com/gmjaguara6replacement.html

 

I too replaced my A6 with a Four Seasons compressor and for some reason didn't have all the complications you did. But mine is a 1975 Series II. Maybe that's why. It doesn't get as cold as the workhorse A6 with R134 though. And the other thing I don't like about the Four Season compressor is the clutch. You can't physically see it pick like you can on the A6. So it's hard to see when it's on. Yes, there is a slight decrease in RPM's but sometimes not enough to know it's picked.

 

I made this change on a completely stock 84 Series III. Fit like a glove. I only had flip that adjuster from in front to behind. There's a picture of that somewhere.

 

I just put that same one in on the V12 and had zero fitting issues. works great.