Another a/c problem on 2002 ford focus

I have had a slew of problems with my 2002 Ford Focus. Just recently, the a/c went out… again. What could it be this time? And how much might I expect to pay?

current mileage: about 90,000

History (Abbreviated)

September 2006, 65,000 mi.: leak found; replaced evaporator core, recharged

May 2007, 72,000 mi.: replaced thermostat housing.

July, 2008: battery replaced; next week, a/c finicky, often no cool air.

July 2008, 88,000 mi.: alternator replaced.

For two weeks following this repair, A/C fine. Then, A/C stops blowing cool air. (In the meantime, engine making grinding, squeaking, and knocking noises.)

August 2008, 90,000 mi.: Replaced clutch, pulley compressor, and field coil; A/C recharged.

August 2008 - TWO DAYS AFTER LAST REPAIR (above), A/C went out (suddenly) - stopped blowing cool air.

Help? Please?

You didn’t replace the orifice tube or the accumulator/drier.

Did you check for leaks after the repair? Is the system empty? Working as a DIY or was this done at a shop? What was the reason for the Aug 2008 repairs? Was it required to discharge the system for the Aug 2008 repairs? Were those engine noises ever delt with?

The engine noises were the reason for the August 2008 repairs(e.g., pulley compressor, etc.), and thus were taken care of. I believe discharge was required for repair. All of this was done at the dealership.