The Complete HVAC Maintenance Checklist for Colorado Homeowners

Spring Checklist (March through May)

Spring is when you transition from heating to cooling. Use this time to prepare your AC for the hot months ahead.

• Replace the air filter. Start fresh for the cooling season.
• Clean the outdoor AC unit. Remove leaves, cottonwood fluff, and debris that accumulated over winter. Gently spray the fins with a hose.
• Check the condensate drain line. Pour a cup of vinegar down the drain to prevent algae buildup.
• Test your AC before you need it. Turn it on and let it run for 15 to 20 minutes. Make sure cold air is coming from the vents and the outdoor unit is running.
• Check your thermostat. Switch from HEAT to COOL. If you have a programmable thermostat, update the schedule for your summer routine.
• Schedule a professional tune-up. A spring AC tune-up ensures your system is ready for the demanding Northern Colorado summer.

Summer Checklist (June through August)

During the cooling season, keep an eye on performance and airflow.

• Check the filter monthly. Summer means more dust, pollen, and cottonwood. Northern Colorado summers are particularly tough on filters.
• Keep the outdoor unit clear. Maintain at least 2 feet of clearance around the condenser. Trim back plants and grass.
• Watch for ice on the refrigerant lines. If you see frost or ice, turn off the AC and call for service. This indicates restricted airflow or low refrigerant.
• Monitor your energy bills. A sudden spike can indicate your system is struggling and needs attention.
• Make sure all vents are open and unblocked. Do not close vents in unused rooms. This can cause pressure problems.

Fall Checklist (September through November)

Fall is furnace prep time. Colorado can get its first snow as early as September, so do not wait until November.

• Replace the air filter. Fresh filter for heating season.
• Test your furnace before the first cold snap. Turn the heat on and run it for at least 20 minutes. Some smell from dust burning off is normal on the first run. If it smells like gas or burning plastic, shut it down and call a technician.
• Check your carbon monoxide detectors. Replace batteries and make sure they are working. CO leaks are most common during heating season.
• Inspect visible ductwork. Look for disconnected sections, visible holes, or damaged insulation in your basement, attic, or crawlspace.
• Cover your outdoor AC unit. A simple cover keeps debris and snow out during the months it is not in use. Use a breathable cover, not a plastic bag, to prevent moisture buildup.
• Schedule a professional furnace tune-up. This is the most important maintenance appointment of the year for Northern Colorado homeowners. A technician will check the heat exchanger, test safety controls, clean the burners, and ensure everything is safe for winter.

Winter Checklist (December through February)

During the heating season, focus on keeping things running smoothly.

• Check the filter every 30 days. Heavy furnace use clogs filters faster.
• Keep vents and returns clear. Do not block them with furniture, rugs, or holiday decorations.
• Keep the area around your furnace clean. No storage, no clutter. Furnaces need clearance for air intake and safety.
• Watch for warning signs. Unusual noises, frequent cycling, cold spots, or a yellow burner flame (should be blue) all warrant a service call.
• Clear snow and ice from exhaust vents. High-efficiency furnaces vent through PVC pipes on the side of your house. Snow drifts or ice can block these, causing the furnace to shut down. Check after every major snowfall.

What Happens During a Professional Tune-Up

When a Mountain States Mechanical technician comes for a maintenance visit, we check and service over 20 points on your system:

• Inspect and clean burners
• Check heat exchanger for cracks
• Test all safety controls
• Measure gas pressure and adjust if needed
• Check thermostat calibration
• Inspect electrical connections and tighten them
• Lubricate moving parts
• Check the blower motor and belt
• Measure airflow and temperature rise
• Test carbon monoxide levels
• Inspect the condensate drain
• Check refrigerant levels (cooling tune-ups)
• Clean and check evaporator and condenser coils

Our Peak Plan maintenance program includes two tune-ups per year (spring and fall), priority scheduling, and discounts on repairs. It is the easiest way to stay on top of your HVAC maintenance without having to remember all of this yourself.