Furnace Maintenance & Inspection

Safety and combustion: visual heat exchanger inspection, combustion analysis where warranted, flue and vent integrity and draft verification, gas leak check at the connections, manifold gas pressure against nameplate, rollout and limit switch testing, and carbon monoxide measurement at supply registers.

Ignition and controls: burner cleaning, hot surface igniter resistance test, flame sensor cleaning with microamp verification, pressure switch operation against actual inducer draft, sequence-of-operation test from thermostat call through blower shutdown, control board and relay inspection, and thermostat calibration and configuration check.

Airflow and mechanical: filter inspection and replacement, blower wheel and housing inspection, blower amp draw against nameplate, total external static pressure measurement, temperature rise across the heat exchanger compared to the nameplate range, condensate drain and trap check on condensing units, and electrical connection tightening.

You leave with a written report: what was measured, what was cleaned, what is trending toward failure, and what if anything needs attention now. No verbal-only findings, and no repairs performed without your approval.

Any company can tick boxes. The value is in the measurements, because those are what predict failure. Flame sensor output in microamps tells you how close the unit is to a lockout before it happens. Igniter resistance drifting out of spec means it will fail this season, not next. Static pressure above the equipment's design means the blower is fighting the duct system every minute it runs.

Temperature rise is the single most diagnostic number on a furnace. Rise above the nameplate range means airflow is short — a filter, a duct restriction, a blower problem — and a heat exchanger running hotter than designed is how cracks start. Rise below the range means the burner is underfiring or airflow is excessive.

That is also how we avoid the two failure modes of maintenance visits: finding nothing because nothing was measured, and finding everything because finding things is profitable. Numbers against nameplate specs make the conversation objective.

October and early November are the right window in the Valley. That gives you time to handle any finding before the first genuine cold night, and it means you are not competing for a slot during the week when every dormant furnace in Maricopa County fails at once.

Skipping it does not usually cause a catastrophic failure — it causes an inconvenient one. The dust-and-idle failures are cheap parts, but they happen at the worst moment, and the no-heat call in the middle of a cold snap comes with a wait that a scheduled October visit does not.

The exception is the safety side, where skipping genuinely matters. Heat exchanger cracks and venting problems develop quietly and produce no symptom you would notice until a CO detector goes off. If you only do one thing on a furnace every year, make it the combustion and heat exchanger check.

Change the filter on a real schedule. During cooling season in the Valley, a 1-inch pleated filter is a monthly item; 4-inch media filters run three to six months. The filter protects the blower and the heat exchanger, and the vast majority of limit trips we see trace back to a filter nobody looked at.

Test the system in October. Set the thermostat to heat, run it for fifteen minutes, and pay attention. Expect a brief dusty smell on the first burn and nothing else. If it does not light, cycles off quickly, or smells wrong after ten minutes, you have found a problem on a mild day rather than a cold night.

Keep the equipment area clear and check your CO detectors. Attic and closet furnaces need service clearance, stored boxes against a furnace cabinet are a fire risk, and a carbon monoxide detector with a dead battery is a decoration. Replace detector batteries when you set clocks back.