A commercial HVAC inspection is usually best done either before the beginning of summer or before the freeze comes near the winter. Depending on whether you live in a colder or warmer area, summer maintenance and inspections might be more or less important than your furnace inspection. So make sure that you keep that in mind before considering what your Denver HVAC might require.
The best approach is to talk to your HVAC contractor and find out what the best course of action is. Inspecting your AC before the summer should be something that is necessary regardless of which state you live in and whether or not the summers in your area are mild. Also, if your cooling system is a little older and has required some repairs in the near past, consider checking for strange noises, greater energy consumption and problems such as bad odors coming from the main unit. You might need to have it checked out again, if any of these symptoms appear.
Commercial HVAC inspections are somewhat more comprehensive than regular residential AC inspections, so expect to also pay a little more for one especially if you own a larger system that caters to a large warehouse or commercial space. Usually the price will increase depending on how large and complex the system actually is.