Air Conditioning (Alfa 33 907 Series)

April 20, 2020 36

Let's now move on to the compressor. Our purpose is to replace every part that needs attention or is ready to fail plus retrofitting items intended for use of R134a instead of the banned R12. A note here: be careful during disassembly as the compressor features very many parts and it is very easy to mix them especially the internal parts.

The compressor used is a Sanden SD-508. The designation 508 actually means it is a 5 piston compressor with 8 Oz. fixed displacement; it is designed for use with R12 and it will be converted for use with R134a. Since R134a is operating at higher Suction and Discharge values, caution should be paid regarding internal parts; since these are designed for R12 it is highly possible for these seals to rapture in contact with R134a.

For this reason, do replace those parts approved for use with R134a in order to give the compressor a few years life extension. If this is not the case then sooner or latter the compressor will fail.

Alfa 33 907 Series Air Conditioning > AC Compressor Repair - Disassembly

Using the vice, lock the compressor pressure plate and use a 17mm socket to undo the lock nut.

Use a pair of flat screw drivers positioned opposite each other in order to remove the pressure plate.

An expanding pliers will help you remove the lock ring which secures the pulley to compressor body.

Use the puller to remove the pulley

Once the pulley is out, the electromagnetic clutch is exposed; remove the lock ring to separate the coupling from the compressor body.

Use a 10 mm socket to remove the compressor front part

This is the first view to see when you remove compressor front part. Notice that the piston assembly is slant; this is so because the pistons are operating one at a time.

Compressor front part, also slant shaped. Notice the rod on the bottom; this is intended as an alignment guide to the compressor body while acting as an oil gallery for the shaft lubrication.

Let's remove compressor cylinder head (13 mm socket is required)

Cylinder head with the gasket. Note the amber shade on the lower bottom of the chamber; this is oxidized refrigerant oil which has turned to a solid substance.

Valve plate assembly.

Valve plate with the respective gasket. Seen here are the valves which follow the same principle as an internal combustion engine.

Compressor body as seen with piston assembly removed. On the center you see a spring which ensures the piston assembly is always firm.

Piston assembly. Notice the yellowish color on each piston; these are traces of oxidized refrigerant oil.

Rear view of compressor body.

Let's remove compressor shaft. Remove the washers (these are actually spacers)

Compressor shaft on the left complete with bearing and front part on the right.

Shaft close-up showing the bearing.

Bearing integrated on the front part body.

Remove felt ring. This acts as barrier between the weather elements and the compressor internals.

Use an expanding pliers to remove lock ring

Remove lip seal. Since there was no suitable tool, a DIY one was used!

That's the lip seal which is fixed to the compressor shaft recess.

Remove the shaft protective seal. This seal revolves along with the shaft as opposed to the shaft seal which is fixed to the compressor recess.
The black material seen on the top of the seal has a very smooth surface (made of carbon) and with the help of oil it slides to the surface of the shaft seal. This way oil acts as coolant (no overheating) and in the same time it makes a perfect seal ensuring no oil escapes outside the compressor.