If you have tried to defrost your air conditioner before, you must already know about evaporator coils. Evaporator coils carry a liquid called refrigerant in your air conditioner. The expansion, contraction, and flow of this liquid help in the efficient cooling of your home.
If the refrigerant is insufficient, your air conditioner will not be able to produce as much cool air as needed, and you will feel uncomfortable. You can refill the liquid if you have experience, but it is always better to ask a professional for help.