Replace parts as written above: accumulator, orifice tube, condenser.
Rent or purchase gauges, and rent a vacuum pump. Make sure you read the directions on the vacuum pump.
Replace all O-rings you remove.
Vacuum the system first, make sure it holds -30 psi for 30 mins or so.
You can get oil charges under pressure like refrigerant. Put in the oil charge, then refrigerant as needed. Be sure to ask how much refrigerant and oil your system requires. Most parts stores can look this up. Verify that the oil charge is sufficient, and make sure you are getting enough refrigerant. If you have to buy extra, the general rule for R-134 is somewhere around 35 psi on the low side when cycling.
I'll look up the actual specs for the Focus sometime when the room the manual is in is not occupied by sleepers.
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Moderating everything now, let me know if I can help.
Originally Posted by the user formerly known as ZX3_Chick
You're special aren't you.