Denver's average first freeze is October 7, but early freezes in late September are common. Temperatures can drop from 70°F to below freezing overnight. Your furnace needs to be ready before that first cold snap — not after you're already shivering.
Replace the filter, test the thermostat by switching to heat mode, listen for unusual noises during the first cycle, check that all vents are open and unblocked, and schedule a professional tune-up. If you smell anything burning during the first run, that's usually dust burning off and should clear within 30 minutes.
A one-time furnace tune-up runs $89-$149. Our Comfort Club at $179/year covers both your furnace and AC tune-ups. Either way, a tune-up is far cheaper than an emergency repair call on the coldest night of the year.
If you're dealing with this issue in the Denver Metro area, the most important thing is getting a proper diagnosis from a NATE-certified technician who understands Colorado's altitude. At 5,000+ feet, HVAC systems behave differently than at sea level — refrigerant pressures, combustion efficiency, and airflow all change with elevation. A technician who doesn't account for altitude can misdiagnose the problem entirely. On Time Heat & Air has been serving the Front Range since 2013 with same-day service, upfront pricing, and no overtime fees for emergency calls. Call (720) 527-0668 for a diagnosis.
Colorado's climate creates unique HVAC challenges that homeowners in other states don't face. Our dry air, intense UV exposure, extreme temperature swings (it's not unusual to see 60°F days followed by 20°F nights), and hail storms all take a toll on heating and cooling equipment. Systems here work harder and fail in different ways than identical systems at sea level.
Brighton, where we're based, sits at 4,984 feet. Denver is at 5,280 feet. Aurora, Lakewood, Arvada, Westminster — they're all above 5,000 feet. That altitude affects everything from gas pressure in your furnace to refrigerant charge in your AC to the amount of air your blower motor needs to move. Every system we install or repair is calibrated specifically for Front Range conditions.
We're licensed in 8 Colorado counties with active, verifiable license numbers displayed on our website. Our technicians are NATE certified — the highest certification in the HVAC industry. And we've maintained a 5.0 Google rating across 70+ reviews because we show up on time, diagnose honestly, price upfront, and fix it right the first time.
NATE Certified · Licensed in 8 Counties · Same-Day Service