Since you have no answers, I'll chime in. Odds are there is an aircon problem you need to have serviced, but as time has passed there may now be more than one problem. As for the original problem of the cabin being cold until driven I would suspect the thermostat is stuck open, but when the temp goes above normal on long trips it leaves me guessing, although it could still be a faulty thermostat. Is something blocking airflow to the airconditioning condenser &/or the radiator?
I'd suspect there are multiple issues, but the easy one will be having the air con serviced.