I'd go to the mold remediation company instead for a consultation, which is free...
Air duct cleaning, according to a few AC pros I spoke with in the past, is not the way to go when it comes to mold. Most remediation companies will first remove all wet surfaces throughout the house (which you can do yourself too). Then they clean the air in all areas of the house killing the spores. Then, they would clean the actual AC with Microban or some other chemical to kill the rest of the mold.
Of course, the process should be finished with the air test from a reputable company.
This is, of course, if the mold is not toxic, which it sounds like it is not.
Hope this helps,
Beachfront Realty, Inc.