Calculating required cooling capacity

[RUFUS2K]

Does anyone have a method (spreadsheet, software package, manual calculation template, etc) for calculating the necessary size of an automotive airconditioning system? I need to take into account the solar load through the windows and body, occupant heat, etc.

I am working on a supplimental cooling system for a vehicle and have to drop the temperature from 105 deg F to 85 deg F in 30 minutes or less.

We have always sized the systems through experimentation, but I would like to take a more engineering based approach.

Thanks!