I thought that if the compressor locked up it meant that the bearings wore out and froze up.

Could it be something else?

Isn't the freon in a closed system?

How would metal particles get into the freon?

Is there a cross section drawing showing the innards?

Just curious.

 

The compressor itself failing is a much bigger problem. Compressors normally fail due to loss of oil, which happens over time. If you have an older A6 type compressor, you can see this oil loss on the underside of the hood, right above the compressor belt. The R4 compressors leak also, but not as much. The seals in A/C compressors are ceramic..no rubber there, so they WILL leak slightly. With a leaky seal, you lose oil AND freon from the system. Most folks simply top off the freon when it gets low, but no-one ever considers replacing the lost oil. If you run your engine with no oil, it will eventually seize...as will an A/C compressor. When the compressor is run low on oil, there is no lubrication, same as the engine. No lubrication means metal parts inside the compressor, such as pistons, and the swash plate(crankshaft, basically) start shedding metal. That metal is circulated thru the entire A/C system, contaminating everything, including the evaporator, condenser, and whatever type of control system it uses, whether it is a VIR, orifice tube, or expansion valve. 

That's why it's necessary to flush the entire system....in a lot of cases, the control mechanism(VIR, orifice, etc) will need to be replaced, as well as the accumulator/dryer. You can't really get ALL of the contamination out of a system without having to replace SOME components.

So....if yer real lucky, a squealing noise, and belt burning could just be the pulley bearing. But..if you cannot twist/turn the compressor clutch by hand .....the compressor is toast...

Joel, can you add to or replace the oil in the A6?  If so how/where?  

Thanks for the help on this - slowly becoming edumacated on this subject, too!  

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

Might be another good option....

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

daveo76 said:Joel, can you add to or replace the oil in the A6?  If so how/where?  

You say can turn the clutch on yours(there is normally some resistance), and the pulley bearing spins freely, but you hear noises when you turn the clutch....that is not normal. With the hoses connected, and assuming there is still a refrigerant charge int he system, you really shouldn't hear anything when turning the clutch. Chances are what you are hearing are the melted guts of the compressor. I can't hear or feel what you are hearing and feeling, so I can't say 100%, but, if it locked down on you before....it'll lock down again. A compressor can get hot, and lock up/seize, but turn fine when it cools down. 

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

It's possible that one or more of the reed plates(valves) has broken, and got down into the compressor, and locked it up that one time. Depending on which reed broke, it might cool ok, or not cool at all, but it would definitely effect the pressures.

 Still....bottom line is, if the thing locked up at one point, and if there wasn't too much freon in it, there is a problem with the compressor. Having too much freon in one will also cause it to lock up. Similar to having water on top of a piston on the engine...it won't compress. 

Bob, can't help with your compressor rebuild, but which aftermarket are you using?  If you do succeed in getting your A6 rebuilt are you planning on selling this one?  

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.

 

Just to add a bit to Joels statement.  The A6 compressor does have an oil reserve.  The A4 does not.   Oil does circulate with the refrigerant with ALL A/C systems.  That is what lubes everything, including the compressor.   That's where the film build up comes from I metioned earlier that creates the seal.  Flushing the system removes the film, and here come the leaks after a refrigerant change over.

 

Due to the fact that, as Joel said, the oil is often not added. Even without leaks showing oil, it can and will disapate with ANY refrigerant leak.  It DOES travel with the refrigerant leak, and that includes leaving the system.   Often oil traces show where the leaks are, but not always.  That depends on the volume of the leak.

 

1976 Silver/Firethorn.  L48, 4spd.  Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.