Duct cleaning may not just give up to its name:
Just duct cleaning may not cut it you have to be able to diagnose many things before a conclusion that duct cleaning will solve the problem there are many factors that can cause contamination like high humidity , oversized air conditioner ”Yes people do think the bigger the better” mold improper or cheap filters ,environment such as smoke ,grease etc…
Things you should know first:
You have to know why the customer is asking to have their ducts cleaned before you begin you must inspect all areas of possible contamination such as the ducts themselves ,air handlers ,fans ,dampers you may ask why because you want to make sure you get to all areas once you start cleaning.
Just regular duct cleaning in the average 3.2 with a 3.5ton air conditioner runs about 20 dollars per drop meaning per grille it goes further than that ask the technician to open up the air handler to inspect the coil ,and blower motor chances are it will be just as contaminate also than all components have to be removed and cleaned so definitely the price may increase at that point you want be sure the technician is certified to handle refrigerant such as EPA ,or NATE.