A few years ago I needed to replace a locked up A-6 on one of my trucks. I could get a O really?'s rebuild for under $150. Since then it lasted two years and then it would get hard to turn sometimes. This would cause the clutch or belt to slip, but if you shut the system down and re started it would continue. Finely it took out the clutch and the whole unit was replaced with a used compressor from the Northwest (Oregon) which likely saw little use.
Today I opened up the old compressor to see what went wrong.
With the guts out of the case, the 1st thing I noticed was when you tried to turn the wobble plate one piston remained stationary while the other two moved freely. So one piston was tight in the bore, it would move with more force applied to the shaft, but it was much tighter in the bore. The next thing I noticed was a fair bit of end play in the shaft. when the shaft was turned and the stiff piston not moving in the bore, the shaft would move fore and aft.
The A-6 is supposed to assembled with selective fit parts, a .0005" preload on thrust bearing Having a zero end play is important for shaft seal life.
Likewise the ball seats that ride on the wobble plate are also a selective fit. It is obvious that this compressor was assembled with what ever parts were to hand, and no fitting was done.
I haven't pulled the halves of the guts apart to look at the piston and rings, but starting with such a mis-match of parts I don't know if I can find what I need to assemble correctly.
Unlike most compressor failures, this one wasn't due to low oil level. I suspect the tight piston would get tighter as the system heated up. I have another compressor that suffered a thrust-bearing failure. May be there will be enough parts to make one good one. If not I'll keep it and the other one for a parts stash.
Today I opened up the old compressor to see what went wrong.
With the guts out of the case, the 1st thing I noticed was when you tried to turn the wobble plate one piston remained stationary while the other two moved freely. So one piston was tight in the bore, it would move with more force applied to the shaft, but it was much tighter in the bore. The next thing I noticed was a fair bit of end play in the shaft. when the shaft was turned and the stiff piston not moving in the bore, the shaft would move fore and aft.
The A-6 is supposed to assembled with selective fit parts, a .0005" preload on thrust bearing Having a zero end play is important for shaft seal life.
Likewise the ball seats that ride on the wobble plate are also a selective fit. It is obvious that this compressor was assembled with what ever parts were to hand, and no fitting was done.
I haven't pulled the halves of the guts apart to look at the piston and rings, but starting with such a mis-match of parts I don't know if I can find what I need to assemble correctly.
Unlike most compressor failures, this one wasn't due to low oil level. I suspect the tight piston would get tighter as the system heated up. I have another compressor that suffered a thrust-bearing failure. May be there will be enough parts to make one good one. If not I'll keep it and the other one for a parts stash.
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