Here are some things to do on a quarterly basis

1. Replace or clean the filter. If you have throwaway filters, replace them. If you have cleanable filters, clean them. Sounds simple, but the fastest route to compressor failure or poor performance from your PTAC
equipment is air flow restrictions. A clogged filter can reduce air flow to almost nothing. Vacuum the filter and replace. If it's really dirty, more thorough cleaning with mild soap and water may be necessary.

2. Check the switch, thermostat, and other functional controls on the unit. Most PTAC units have unit mounted controls, and things get spilled, push buttons break, and knobs disappear. Replacing knobs and buttons and making sure switches and thermostats operate easily will prevent users from using improvised tools to push and turn.

3. Check the power cord for breaks in the insulation, especially on units that do not have the new LCDI cords. Also make sure the plug fits snug in the receptacle. A loose plug can arc and be a fire hazard or cause problems for other electrical components.

4. Remove anything from the top of the unit that might cause problems, such as liquids that can spill into the unit.

On an annual basis, a more thorough inspection and cleaning may be necessary. Since PTAC units are directly exposed to the outdoors, they tend to get debris and other undesirable things inside them. These steps should be performed by a trained professional:

1. Clean out any debris (leaves, lint, paper, the occasional dead critter). Check where the unit seals against the wall sleeve for air leaks and repair as needed. Being directly exposed to the elements, a PTAC that does not seal properly will give the appearance of not functioning properly.

2.Clean the coils. Clean out large debris with a vacuum or compressed air. Use a commercial coil cleaner to get the really stubborn dirt. Be careful when cleaning the evaporator coil to use a coil cleaner designed for the indoor coil. Some of the cleaners for outdoor coils are acid based and are caustic, so take necessary precautions and wear recommended safety gear. Clean the drain pan, clear any drain holes or hoses, and let the PTAC unit dry.

3. Check the fan blades and blower wheels and shrouds for mold or fungus. Also check any insulation for same. Normally mold cannot grow on insulation, but it can grow in the dirt and dust that collects on the insulation. Vacuum off any dust or dirt. Treat with an antibacterial/antifungal cleaner, rinse and let dry thoroughly.

4. A PTAC normally has one or two fan motors. Some of the motors have oil ports. Oil the motors as necessary per manufacturers specifications.

5. Clean the inside of the PTAC sleeve/cabinet. Remove any obstructions from drains, check and repair any gaskets, and clean with an antibacterial/antifungal cleaner.

6. Finally, check for anything near the PTAC unit, both inside and outside that might impede performance. Trees or shrubs on the outside may need to be trimmed, mulch pulled back, etc. Inside, boxes, desks or other items too close the unit may cause airflow problems. Move these away as necessary.