Fort Collins gives you about a month of warning. April is mild, May warms up, and by July the city is logging most of its roughly 30 days a year at or above 90°F. Your air conditioner has sat idle since September, collecting dust, leaves and pollen, and it is about to run its hardest six weeks of the year — at 5,003 feet, where it already loses roughly 10–20% of its sea-level rated capacity. A pre-summer clean is the cheapest insurance you can buy for that season, and most of it is straightforward homeowner work.
How to clean and maintain your AC before summer: start inside with the filter and the drain
Replace the filter first, before you do anything else. A filter that has sat all winter is loaded with dust, and a clogged filter is the single most common cause of weak cooling and frozen coils. Match the filter to what your system was designed for — a MERV 13 filter in an older furnace not built for it chokes airflow and can cause the problems you are trying to prevent. During wildfire smoke season, check filters monthly; MERV 13 or HEPA filtration plus activated carbon is the right defence, and UV lights do not remove smoke.
Next, find the condensate drain. It is the small PVC line running from the indoor unit to a floor drain or outside. Pour a cup of water mixed with a little white vinegar through the access tee, or check that water actually flows when the system runs. A clogged drain is the most common source of water on the floor beside an air handler, and it is also the easiest failure to prevent. If the drain line runs through an unheated space, remember it can freeze in winter — but in spring, the job is simply to confirm it flows.
Outside: the condenser coil and clearance
Turn the power off at the outdoor disconnect before you touch the condenser. Then clear everything within about two feet:
- Leaves
- Grass clippings
- Stored lumber
- The shrubs that grew into it over winter
Foothills dust and pine pollen are the local load — they coat the coil fins and insulate them, so the unit cannot shed heat.
Rinse the coil gently from the inside out with a garden hose on a low setting, working top to bottom. Never use a pressure washer and never scrub the fins with a brush; bent fins block airflow worse than the dust did. Straighten any bent fins with a fin comb if you have one, and leave it at that. If the coil is caked with grease or the fins are badly damaged, that is a technician job, not a hose job.
Run a test cycle in April, not July
Once the filter is fresh and the coil is clean, run the system on a mild April afternoon and check three things. First, air from the supply registers should feel clearly cool within a few minutes — roughly 15–20 degrees below the return air. Second, the outdoor unit should run steadily without short-cycling on and off. Third, listen: grinding, squealing or a loud buzz from the outdoor unit means a failing motor or contactor, and that is a repair to book now, in the shoulder season, when it is routine rather than an emergency.
Also check the thermostat. Replace the batteries if it has them, confirm the cooling setpoint, and make sure the fan is set to AUTO rather than ON — a fan left on ON runs the blower all day and can make the air feel clammy. If you have a smart thermostat, confirm it is still connected and its schedule matches how you actually live now, not how you lived last summer.
What to leave to a technician
Refrigerant is the bright line. If the system is low on refrigerant, it has a leak, and finding and fixing a leak — and handling refrigerant, which follows EPA Section 608 rules — is licensed technician work. The same goes for electrical work inside the condenser, capacitor replacement, and anything involving the control board. A professional AC tune-up in Fort Collins runs $80–$150 (Cool Ducts and Allen Service, 2026) and covers the coil cleaning, refrigerant check, capacitor and contactor testing, and a full cooling-cycle test that a homeowner clean cannot. Book it in March or April, and if the system is past 15 years old, ask for an honest read on its remaining life — AC life in Fort Collins is about 15–20 years — so a replacement can be planned in spring rather than forced in July. If your home still cools with a swamp cooler, the pre-summer question is different: evaporative coolers work in dry June and fail in humid August, and a conversion to refrigerated cooling is worth pricing before you spend another season on the old unit.
Professional tune-up, at a glance.
| Item | Published figure | What it covers |
|---|---|---|
| Professional AC tune-up | $80–$150 (Cool Ducts and Allen Service, 2026) | Coil cleaning, refrigerant check, capacitor and contactor testing, and a full cooling-cycle test |
Get help with HVAC in Fort Collins
Do the homeowner steps in April, book the professional visit in the same month, and your system will be ready for July. DNA Refrigeration Heating & Cooling handles AC tune-ups and air conditioning maintenance across Fort Collins — call us at (970) 932-2324. We are open 24 hours, 7 days a week.