Teardown and comparison of the DA6 and HR6 compressors. The compressors are externally almost identical, so telling them apart is nearly impossible, unless the original sticker is still on it and readable. First, the original DA6 from my 84 Fiero SE. I removed the clutch hub, pulley, and clutch coil, and cleaned the end off with a wire wheel. Sometimes these can get REALLY dirty, and the best way I've found to clean them, is to plug the ports on the back, spray the compressor down with engine degreaser, and hose it off. You want it to be as clean as possible before opening it.
Remove the 6 bolts with washers, and remove the front head. This reveals the head gasket and front valve plate
From left to right: head gasket, valve plate, and suction reed
Top of the compressor with the above parts removed, showing the cylinders and pistons
Rear head removed, as it came off, showing the rear suction reed.
Rear head with the head gasket, valve plate, and suction reed removed.
If you look closely at the inner ring here, you can see two holes drilled into the casting. These go to the other side, where the pressure switches are.
Top of the rear head
Exploded view of the compressor
Front of the HR6 compressor. Completely identical.
The through bolts, completely identical as well.
Front head removed
Back of the HR6
Front shaft cleaned with a red scotchbrite pad, so the new front seal will actually seal.
Front head viewed from the back, showing the back of the suction reed. Notice the diamond-shaped portion.
Another head gasket and valve plate
Front head casting, identical to the DA6, just cleaner
Comparison of the two front heads, DA6 bottom, HR6 top
Front seal removed. With the compressor assembled, this requires a special tool. With the compressor apart, you can just punch it out from the rear with a screwdriver and hammer.
With the seal removed, there is still an o-ring down in the bore. a curved hook makes removing it a breeze.
New seal kits to rebuild the compressor. On the left, the new front seal, o-ring, and installation tool. On the right, the new seals for the compressor, including the large body seals and head gaskets.
Rear head removed
Rear head, note again the diamond shaped part
Rear heads comparison, the casting is identical, the only difference is the machining. The rear head on this HR6 does not have a second switch. The indentation is there, but they didn't drill the hole, or machine the recess for the snap ring.
Comparison of the front and rear valve plates, they are different
The center section separated, showing the pistons. Notice the small o-ring at the bottom. This is also included in the above kit.
Reassembly is the reverse, with new seals coated in mineral oil, even if you're doing an R-134A conversion. In the case of this HR6, I had to reclock it to use it in the Fiero. This is what the correct compressor clocking looks like:
[This message has been edited by RWDPLZ (edited 08-25-2012).]