Air Conditioning - Help,. copper line replacement

Recently I had my central air conditioner unit replaced, the company said I did not need to replace the copper line that goes from the furnace to the outside unit as long as the fittings matched up, did I make a mistake? I read that the oldline may have a build up of debris and if not replaced and can effect the performance of the new unit. advice? gary

if the old unit(condenser section)didn't have compressor burn outs or constant freon top offs during the previous years they are like new within..did he replace the liquid line dryer and give you new freon with that condenser changeout?changing the piping run out is rare no matter what end is replaced same as the wiring it all stays..the freon should be new NEW meaning different type from the original if required but if you never had freon added the piping is tight and he only made 2 torched connections at the new condenser,and a 3rd and 4th if the LLdryer was replaced

If old and new units are R22, you're ok.

If old was R22 and new is 410A, should have replaced line due to different oil.

Otherwise, as sminker said.