Like all household appliances, portable air conditioners need to be regularly maintained to ensure that they continue to operate properly and efficiently. Thankfully, there are a number of fairly simple things that you can do and look out for to ensure that your portable air conditioner will continue to work as it should for as long as possible.
Where your portable air conditioner is located is essential to its proper operation. Keep it out of extremely dirty or dusty rooms (or clean those rooms if you can't move your air conditioning unit), because these particles will quickly collect within your air conditioner's air filter, reducing its efficiency over time.
Replace/Clean the Filter
In a similar vein, you'll want to check and either clean or replace your portable air conditioner's filters fairly regularly. Though it will depend on the environment that it is installed in, the type of filter, and how often the unit is operating, as a general rule of thumb you should check and clean or replace your filter every three months. Whether or not you have to clean or replace your filter will depend on the type of filter you have installed: check the documentation that came with either the filter or air conditioner to determine what to do.
Check the Hose
Check the hose (or hoses, depending on the model) of your portable air conditioner for moisture every time you replace the filter, and clean it out if necessary. This prevents water from running into the unit, which can cause damage, and mold and mildew growing within the hoses, which can be a health hazard within your home. Keeping the hose as straight and short as possible can help reduce the amount of moisture that collects within it.
During the winter months, or whenever else you aren't using your portable air conditioner, be sure to properly drain the unit. To do this, switch the unit onto high on the "fan only" setting to remove any built up moisture. Then, cover the unit (preferably with a plastic tarp, as this won't absorb water) to prevent dust from collecting within it and leave it in a cool, dry place until you need to use it again.
Call a Professional
If your portable air conditioner is not working properly and you can't identify and fix the problem, it's a good idea to contact a professional at websites like http://www.controlledcomfort.com to come look at your unit to find out if it is in need of repairs or replacement.