salemicf

I have a 2002 Legacy with AC problems. I have 56,000 miles on it. All my original miles. I need to geit it fixed. Th "O" rings were replace but only held up for 2 weeks before the AC quit. I was quoted $500 to $1000 for the repair. I was also told the dash needs to be removed in order to perform the repair.. I'm hoping it will be worth fixing. Will the cost run higher after the dash is removed? Can the dash be replaced w/o difficulty? I read on this site that the thermosensor may need replacing together with the expansion valve. I am a retiree & don't use my car very much but I live in Las Vegas NV & right now it's 107 degrees. I have also replaced the head gasket. I would appreciate any input on repairing the AC in my 2002 Legacy