Fall is a season of transition in terms of your HVAC system. At the beginning of fall, you may still be using your air conditioner, but by the end of the season, chances are good that you'll be heating your home. It's important that during this time, you do some preventative maintenance on both components of your system so that your heater functions well all winter and your AC is in good shape when spring comes. Perform the tasks on this checklist as fall rolls in.
Rake leaves out from around your AC unit.
Debris around your AC unit can lead to accelerated rust and wear, and it can also decrease the efficiency of the unit. Fall is the time when leaves and other debris tend to accumulate, so make sure you stay on top of cleaning this mess away. Ideally, you should have all of the leaves raked up before the snow falls so they don't absorb moisture and hold it against the unit all winter and spring.
Cover the top of your AC unit.
If you have a cover made specifically for your AC unit, you can put it on once you're done using the system for the season. However, you should never use a makeshift AC cover (one that you design yourself) because it may do more harm than good by trapping moisture against the unit. If you don't have a cover, all you need to do to winterize your AC condenser is set a few boards on top of it to ensure snow does not get into the fan. Hold the boards down with rocks or bricks if needed.
Change your air filter.
You should be changing your filter monthly anyways, but if you've been slacking on this duty, fall is the perfect time to catch up. When your filter is clean, your furnace will run more efficiently, so you can start the year out with lower energy bills. For most people, a simple, low-cost, disposable filter is perfectly fine, but you can invest in a reusable, washable filter if you wish. While you're at it, set a reminder in your phone so you don't forget to keep changing the filter each month throughout the heating season.
Check your thermostat calibration.
Fall is a great time to check your thermostat calibration. If something is off and you need to have it repaired, it won't be quite as sweltering hot or exceedingly cold as in the summer or winter. Set your thermostat for a certain temperature, and bring another thermometer (that you know to be calibrated and reliable) into the room. Make sure the temperatures are within a degree or two of each other. If the temperature on your thermostat is off, you may wish to have the thermostat repaired or replaced by an HVAC specialist so that when winter hits, you know the temperature your thermostat is displaying is accurate.
Make sure your carbon monoxide detector is working.
Before your turn on the furnace for the season, make sure the batteries in your carbon monoxide detector are fresh, and press the test button to ensure it's working properly. Also, check the back of the detector for a replacement age. (Many say they should be replaced after 10 years.) Replace the carbon monoxide detector if it has reached this replacement age. This way, you know that if there is a leak, it will be detected before it puts you or a family member in danger.
Run your furnace and listen for strange noises.
It's a good idea to turn the thermostat up a few degrees to cause your furnace to run before it gets so cold that you really need it. If you wait until it's really cold to turn your furnace on and find that it's not working properly, you'll have to shiver while you wait for it to be repaired. Listen for noises the first time you run your furnace. Also, make sure it actually warms your home, and then shuts off when the temperature reaches the one you selected on the thermostat. If you hear any strange noises or the furnace does not seem to be blowing out warm air, contact an HVAC specialist. It's better to get heating repairs done now than when it's freezing out!