Fall HVAC Inspection Checklist Before the First Cold Front

Kingwood, TX homeowners: Houston’s first real cold front usually arrives between Halloween and Thanksgiving, and overnight lows drop into the 40s. Most no-heat emergencies hit in the first 2 weeks after the first front, when furnaces that have been sitting idle since February are asked to fire on a 45°F morning. A 45-minute fall inspection catches the four most common no-heat triggers — dirty flame sensor, cracked ignitor, stuck reversing valve, and tripped rollout switch — before the dispatch queue blows up.

Step 1 — Pull the cover and inspect the burner compartment

Open the burner door, slide out the burner, vacuum the burner box, and inspect the heat exchanger for visible cracks when you shine a flashlight through it. A single hairline crack in the heat exchanger is enough to bypass combustion gas into the supply air. CO rises above 35 ppm on the supply side and above 9 ppm on the return side; both should be logged. Replace the furnace on any of those conditions.

Step 2 — Test the ignition sequence end to end

Lower the thermostat by 5°F to call for heat, and time the full sequence. Draft inducer startup (2–5 sec), pressure switch close (within 1 sec), hot-surface ignitor glow (3–6 sec), gas valve open, flame sense (>2.5 µA). Anything outside those windows points to a worn ignitor, a slow pressure switch, or a slow gas valve. An ignitor or flame sensor that fails once will fail again within weeks.

Step 3 — Check the draft and venting

Run combustion analysis on a gas furnace: O₂ between 5–7%, CO under 100 ppm air-free, draft -0.02––0.08 in. w.c. Anything outside those ranges points to a cracked heat exchanger, a blocked vent, or oversize orifice. For a heat pump, verify the auxiliary heat strips fire and the strip relays hold properly. A strip that burns through one cycle then trips the high-limit switch is unsafe.

Step 4 — Cold-climate prep for electric heat and heat pumps

Test the backup heat strips on every level of the system — 5 kW and 10 kW strips should each show a steady-state voltage of 240V at the strip terminals. Loose strip connections oxidize during summer and fail on the first heat call. If you have a heat pump, cycle to emergency-heat mode and verify the strip-only operation produces stable airflow. Some homes run strip-only entire cold snaps when a heat-pump refrigerant leak goes unnoticed in cooling mode.

Step 5 — Logbook and customer follow-through

Every fall inspection should end with a written report listing observed condition, test results, parts approaching end of life, and recommended next-season work (e.g., ‘ignitor showing 3.2 amps, plan replacement within 12 months’). Carry this forward to the spring tune-up so trends are visible. Most homeowners don’t realize how much deferred maintenance costs them until they see the trendline.

HVAC247PRO serves Kingwood from our dispatch zones covering Kingwood Greens, Woodland Hills, Royal Shores, Kings River. Common jobs in Kingwood include homes in the 77339, 77345, 77346 zip code area and near Kingwood Town Center, Greens Park, West Fork San Jacinto River. Typical overnight call-to-driveway time across Kingwood is 35–75 minutes depending on the dispatch zone and time of day.

Key steps for Kingwood homeowners

• Schedule the fall check in September or early October — wait times spike after the first front.
• Have CO detectors at every sleeping area and on each level — test before the first cold front.
• Confirm the gas is on at the meter; many homes have a seasonal gas shutoff that the homeowner never re-lights.
• Replace thermostat batteries and verify the schedule is in heating mode.
• Locate your main water shutoff and label it ahead of any freeze-related emergency.