Air Purifiers

My air filter was inserted incorrectly and now dirt particles are stuck in the heat pump coils. I only have a 4" space to run a vacuum across the coils. Other than to remove the duct work, how would anyone clean these return coils? Seems very dirty and difficult to access.

I had a proffesional duct cleaning company brush the ducts, fog the system, clean the coils and fan in air handler unit, and there is still odor when system is on. Is there any deodorizer or air sanitizer on natural basis?