While there are a number of commercially available coil cleaning solutions on the market, air conditioner coils can be cleaned with a solution of a mild household detergent and water. The detergent and water mix is applied to the coil using a low-pressure sprayer.

I recommend doing this every 2_3 years to keep your FCU efficient.

whenever you are suffering from high humidity levels, try the following:
1. cleaning the coil because the dirt on it hinders dehumidification process.
2. replace thermostat and check the DRV.