Most Lennox calls in San Leandro involve a gas furnace in a hall closet, garage or attic, the central air conditioner paired with it, or a heat pump that replaced both. The failed part is usually ordinary: an igniter, a flame sensor, a capacitor, a clogged drain. What makes Lennox different is that the same brand sells conventional equipment and fully communicating systems, and the two are diagnosed differently, so the first step is pinning down exactly which Lennox equipment you have. You get the price before any work begins. We are an independent service company, not affiliated with Lennox.
Which Lennox equipment do you have?
Lennox sells several tiers, including the Elite Series, and the badge alone does not say what is inside. The model number does. These are the types we see most:
| Equipment | Examples | What it means for the repair |
|---|---|---|
| Variable-speed gas furnace | SL280V | The blower speed is set electronically, so weak airflow can be the motor, its setup or a duct restriction |
| Two-stage air conditioner | XC21 | Runs on low stage most of the time; some faults show only on high stage, so both get tested |
| Variable-capacity AC and heat pump | XC25, XP25 | The compressor is driven by an inverter control, not started through a simple capacitor and contactor |
| Communicating thermostat | iComfort S30 | On iComfort-enabled equipment, runs the system over data wiring and shows alerts on its screen |
| Air purification | PureAir | Needs its replaceable parts serviced on schedule; see indoor air quality |
Common Lennox service calls
| What you notice | Likely cause | What it usually takes |
|---|---|---|
| Furnace lights, then shuts off after a few seconds | Dirty flame sensor or poor ground | Cleaning or replacing the sensor, checking the ground |
| Inducer runs but the burners never light | Pressure switch, blocked vent or failed igniter | Testing the startup sequence step by step |
| iComfort shows an alert and the system stops | Communication wiring, a sensor or a control board | Reading the alert, then testing the wiring and the boards |
| Weak airflow from every register | Clogged filter, blower setup or motor fault | Static pressure and motor tests |
| Heat pump frosted over on a cold morning | Defrost sensor or control, or low airflow | Defrost test and airflow check |
| Water around the furnace in summer | Clogged condensate drain from the AC coil | Clearing the drain, checking the float switch |
Communicating systems: start with the thermostat
When a Lennox system is set up as a communicating system, the iComfort thermostat is part of the equipment, not just a switch. It talks to the furnace or air handler and to the outdoor unit, sets blower speed and compressor output, and posts an alert when a component drops out. That helps the diagnosis: before touching a part, we look at what the system reported. It also means two things for owners. A loose or corroded conductor in the thermostat cable can stop the whole system, so the wiring is tested before any board is condemned. And swapping the thermostat for a generic one can cost you the staging and variable-speed control you paid for. Ask before you replace it; our thermostat installation page covers compatibility.
Have these ready when you call
- The model and serial number from the data plate on the outdoor unit and from the label inside the furnace or air handler door. A phone photo of each is enough.
- The thermostat model and a photo of any alert on its screen.
- Roughly when the system was installed and whether it was registered with Lennox.
- When the problem happens: at startup, after an hour of running, only on cold mornings.
The serial number usually encodes the manufacture date, which tells us the age of the equipment and helps settle warranty questions.
Parts and warranty
A capacitor or an igniter is a standard part and is often replaced on the first visit. Variable-speed blower motors, inverter components and iComfort-compatible control boards are Lennox-specific: they must match the model and serial number, and we check that the exact part is available before quoting. A covered part keeps the Lennox parts warranty, whose length usually depends on whether the equipment was registered after installation, so keep that record with the house papers. Labor falls outside the manufacturer’s coverage; our own repairs carry a 90-day warranty.
Repair or upgrade?
One failed part on a Lennox system that otherwise runs well is a repair. A failed compressor, a cracked heat exchanger or repeated board failures on an older system is a different conversation. Our guides to furnace repair vs. replacement and AC repair vs. replacement walk through it, and we handle furnace installation and AC installation when replacing is the better choice. Comparing brands for a new system? See Lennox vs. Carrier and Carrier vs. Trane.
Local notes
Lennox heating calls in San Leandro, San Lorenzo and Castro Valley cluster between November and March. Variable-speed Lennox furnaces and heat pumps run long, quiet low-speed cycles that suit our mild climate, but all that run time moves more air through the filter, so check it more often than the calendar suggests. A yearly furnace tune-up in the fall catches dirty flame sensors and weak igniters early.