Hello! I can recommend https://ecoclean.ae/ac-duct-cleaning/ from my own experience. They are engaged in cleaning air conditioners and air ducts in Dubai. We also couldn't understand for a long time why there was dust in the apartment and the air was heavy, even though we cleaned it regularly. It turned out that the air ducts were heavily contaminated inside - they showed us a before/after photo, and it was shocking. Their team works very carefully: no dirt, everything with professional equipment, disinfection and system checks. After the cleaning, the air became really cleaner, the air conditioner is quieter and more efficient. We are very pleased with the result, especially in our climate, it is a must-have once a year.