I have a judgement against me for an old medical bill, they froze my account and took the money out, if I pay them in full does that money that was froze get put back into my account?

If the money is frozen, that means you're kept from withdrawing it. If they took the money out, then you only owe them the balance.

Example: If your bill was $1,000 and they took out $250, you would only owe them $750. It would be pointless to mail them $1,000 because then you're paying them money that they've already gotten.