1986 300 ZX Turbo changing coolant

Once again, another air conditioning question with the Z's. Had it fixed about
10 yrs ago, or so I thought. Now, it's blowing hot air through the vents w/o
anything being turned on. Put on the air conditioning, hot air blows. Tried it
again the next day, and it worked. Tried it again and it didn't! Called a shop
about it and he said I'd have to have the Freon removed and put in the new
coolant they are using. Will that be ok with this car?? BTW just had it
painted....looks awesome.