Cleaning Filters

Filters require cleaning or replacement (depending on the type) because as they accumulate dirt, they block up, reducing airflow and hence the cooling capacity of the air conditioner. In addition some types lose filtration efficiency as they get dirty.
There are a large number of different types of filter with different requirements.  If you have a proper maintenance manual for the installation, refer to the manual for cleaning advice. If you don't have a proper manual, the main types and their normal cleaning requirements are as follows: (If you are unsure speak to your contractor or phone Clive Blanchard, Consulting Mechanical Engineer). In some cases more frequent cleaning may be required.
Return air grille filters: these filters are generally in hinged filter frames attached to the return air grille. These filters are really residential filters, unless they are used in conjunction with another higher efficiency filter or air cleaner. These filters are generally of the washable type and should be cleaned by gently washing with water. If they won't clean, use a mild detergent.  These filters usually require very frequent cleaning, at least monthly, and often more frequently.
Deep bed filters: These are large filters usually 400 to 600 mm deep. These may be of the washable or disposable kind. The life of these varies depending on the design and the amount of dust they are subject to. In general you should get at least 12 months life, and sometimes up to three years life between cleanings or replacement. It is generally better to get your air conditioning service company to service these.
Electronic Air Cleaners: These may be stand alone units or incorporated into the ductwork. The cores generally require cleaning approximately once per month.
Other types of air cleaner: There are a number of other types of cleaner. Refer to the manufacturer's literature for details of maintenance requirements.