Step 1 – With the thermostat in the off position, locate and remove your air filter. Step 2 – Using a garden hose with good water pressure, spray off the filter – from both sides. You can repeat this process several times if the filter is very dirty. Just be careful not to use too much pressure or damage could be done to the filter media. When the water runs clear and the filter is clean you are ready for the next step. Step 3 – Shake off the excess water. It is a good idea to let the filter sit out and completely dry before reinstalling it. But if it is still a little damp, you can go ahead and re-install it. Step 4 – Slide the air filter back into the rack, noting proper airflow direction, and you are done. Now you can turn your thermostat back on and remember to do this again next month.