A Lennox gas furnace that lights and drops out, an air conditioner that hums without cooling, a system due for its yearly check: those are the Lennox calls we take in Fremont, Newark and Milpitas. Lennox, founded in 1895 and based in Richardson, Texas, builds furnaces, air conditioners and heat pumps in three tiers, and the tier tells a technician a good deal about what is inside before the panel comes off. Most repairs still come down to one ordinary part. You get the price before any work begins. We are an independent service company, not affiliated with Lennox.
Merit, Elite or Signature Collection
| Tier | What you usually find | What it means for service |
|---|---|---|
| Merit Series | Simpler equipment, mostly single-stage | Standard parts; often fixed on the first visit |
| Elite Series | Mid-range, with single-stage, two-stage and variable-speed options | Check which stage fails; blower setup matters |
| Signature Collection | The top tier, with variable-capacity and communicating models, often run by an iComfort thermostat | Read the system’s alerts first; boards and motors are model-specific |
Lennox furnace repair: what usually fails
- Burners light, then shut off within seconds. A dirty flame sensor or a weak ground. Cleaning or replacing the sensor and checking the ground usually solves it.
- Inducer runs, burners never light. The pressure switch or its hoses, a blocked vent, a full condensate trap on a high-efficiency furnace, or a failed igniter. We test the start-up sequence in order instead of guessing.
- Short heating cycles. A clogged filter or a restricted return makes the furnace overheat and trip its limit switch.
- Blower will not run, or runs noisily. The motor, its capacitor on older single-speed blowers, or the electronics of a variable-speed motor.
- Water at the base of the furnace. In winter, the furnace’s own condensate drain; in summer, the drain from the AC coil above it.
Every repair starts with these checks, and you see the price before parts are changed. More on our furnace repair page.
What a Lennox maintenance visit covers
Fall, heating side
- Flame sensor cleaned, igniter and burner flame checked.
- Inducer, pressure-switch hoses and vent checked; on high-efficiency furnaces the condensate trap and drain flushed.
- Heat exchanger inspected where it is visible, and safety switches tested.
- Filter replaced or checked, blower cleaned if needed, temperature rise measured.
Spring, cooling side
- Outdoor coil cleaned; capacitor and contactor tested under load.
- Refrigerant performance measured rather than topped off by habit.
- Coil drain cleared and float switch tested.
- Thermostat schedule and any iComfort alerts reviewed.
Details in HVAC maintenance, with local pages for furnace maintenance in Fremont and AC maintenance in Fremont.
iComfort: the thermostat as a diagnostic tool
On compatible Lennox equipment, an iComfort thermostat shows alert codes and service reminders on its screen, and the Wi-Fi models pass them to the app. A photo or screenshot of the alert gives the technician a head start before arriving. If you would rather use a different smart thermostat, the answer depends on the equipment: conventional Merit and Elite systems usually accept one easily, while communicating Signature systems can lose staging and variable-speed control without iComfort. Our smart home guides explain the trade-offs.
What to have ready
- Photos of the furnace or air handler label (inside the door) and the outdoor unit’s data plate.
- Any alert on the iComfort screen or app.
- Roughly when the system was installed, and any installation paperwork.
Parts and warranty
Igniters, flame sensors and capacitors are standard parts. Variable-speed blower motors and communicating control boards are Lennox-specific and must match the model and serial number; we confirm the exact part before quoting. We use factory certified parts only. A covered part keeps Lennox’s parts warranty, whose terms depend on the model and the install date; labor is not included. Our repair work carries a 90-day workmanship warranty. When replacement is the better choice, new systems start with a free in-home estimate; see furnace installation.
Local notes
Hillside homes toward Mission San Jose have sun-loaded rooms that keep the air conditioner running on hot afternoons from June to September. In the older tract homes of Fremont and Newark the ducts run through the attic or crawlspace, where a crushed or disconnected run can make a healthy furnace look weak. Heating runs from November to March, so the furnace tune-up is best booked in early fall. Local pages: Lennox in Fremont, Newark and Milpitas.