Air Conditioning Compressor Rebuild

When I installed air conditioning in the Miata I started by rebuilding a used compressor with a gasket kit and new front pulley bearing. There were not many references, hopefully these photos are helpful for anyone else rebuilding their AC compressor.

The first replacement pulley bearing I ordered was the wrong size, I recommend measuring the ID and OD of the bearing and finding an exact replacement. I’m not sure how many variations there were across different years of Miata air conditioning compressors.

AC compressor with front pulley removed
R134a OEM Denso air conditioning compressor
Front of the AC compressor, with felt pad visible

Not sure what the purpose of that felt pad is, but I kept it installed on my compressor.

Removing main bolts from the AC compressor with it held in the bench vise
Front half of the AC compressor removed
Arrows pointing to two bolts that are easy to miss attaching the back half of the compressor

The sections of the compressor were hard to separate after years sealed, but also because some of the bolts holding it together were not obvious. Two sneaky bolts are labeled in the image above.

Back half of the AC compressor removed

This projects was very messy, compressor oil everywhere by the end, even with the plastic sheet.

Using a hammer to separate the back of the compressor housing

Some percussive force was required to separate the compressor sections.

Using a screw and hammer to separate the center section of the compressor
Prepping the compressor middle section for fresh paint

Some black engine enamel was spayed over the surface rust on the main compressor housing.

Full exploded view of the AC compressor ready for reassembly
All parts of the AC compressor arranged for new gaskets and assembly
Front of the compressor being bolted back on
Reassembled AC compressor side view
New bearing being pressed into the front pulley with the bench vise

The bearing went in the freezer overnight to shrink its diameter a bit before pressing it into the pulley.

Reconnecting the front clutch to the compressor, with spacer shim washer

The small washer keeps the spacing of the compressor clutch in spec for the electromagnetic to engage the clutch.

Threaded mounting holes for AC compressor bracket on the Miata engine block

Later when replacing the power steering pump belt tensioner a 10mm x 1.25 tap was used to clear out these thread. They were crusty after 25 years of exposure on the side of the motor.

AC compressor bracket bolted to engine

The compressor bracket also got a fresh coat of black engine enamel. The top-front corner needed to be shaved off later to clearance the new Flyin’ Miata belt tensioner.

Fully rebuilt AC compressor ready to go in the engine bay
Installed refurbished AC compressor

This compressor rebuild job was successful and has been working perfectly without leaks since 🤞 (as of Feb 2024). The clutch was pretty worn on this old compressor, so it does have some occasional slipping and squealing. I bought a replacement clutch to be installed in a future post.

Santech A/C Compressor Gasket Kit MT2141$20
A/C Compressor Clutch Bearing 30mm ID x 52mm OD x 22mm Thick CB-1101$16

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