I presume that when you dispose of this car that you will expect someone to exchange money for it. If it came to my shop I would tell the prospective purchaser to deduct $2000 for an inoperative A/C. It is a fair risk assessment as a lack of A/C can mean many things. If it is possible to get A/C for less than that consider it a short term investment with the dividend being your comfort.
Bosch Master, ASE Master, L1
33 years MB technician