Furnace and heating repair in San Jose, CA

San Jose has mild winters with cool nights and chilly, damp mornings. Heating runs regularly for a few months without ever working at its limit. Gas furnaces are the familiar setup in South Bay homes, often tucked into a hallway closet, the garage or the attic, and many older homes have a furnace with no central AC.

Heat pumps are becoming more common as homeowners add cooling and replace aging gas equipment with one electric system. If your outdoor unit runs while the house is heating, you have a heat pump, and the heat pump not heating guide is the better starting point.

Because the climate is gentle, furnaces here can stay in service for a long time, and age-related faults are common: worn igniters, dirty flame sensors, tired blower motors and cracked or rusted parts on equipment that has seen many winters.

Run through these first. They are the only checks that are safe without opening the equipment.

• Set the thermostat to Heat, raise the setpoint a few degrees above room temperature and replace the batteries if it has them.
• Check the breaker panel for a tripped breaker on the furnace, air handler or heat pump. Reset it once. If it trips again, stop and call.
• Find the power switch on or near the furnace or air handler, which looks like a light switch, and make sure it is on.
• Pull the filter. If it is gray and matted, replace it. A clogged filter can make the system overheat and shut itself off.
• Open the supply registers and clear furniture or rugs away from the return grille.
• Clear leaves and debris from around the outdoor unit if you heat with a heat pump.
• Write down any error code on the thermostat or the blinking light pattern visible through the furnace's sight window.

The technician confirms the symptom, reads any fault code and tests the likely parts. For a gas furnace that usually means the igniter, flame sensor, pressure switch, inducer motor, limit switches and blower. For a heat pump it means capacitors, the contactor, the reversing valve, the defrost control and the refrigerant charge.

Expect a diagnosis and a written price before the repair starts. Ask what failed and why, and whether the part is covered by a manufacturer warranty. Ask to see the failed part.

California contractors are licensed by the Contractors State License Board (CSLB), and heating work falls under the C-20 classification. Look up the company with CSLB's Check a License tool before the visit; the California license lookup guide shows what to read on the record. CSLB says C-20 contractors must carry workers' compensation or have a self-insurance certification on file.

A part replacement is a repair. Replacing the furnace or installing a heat pump is a bigger job: CSLB says most alterations require a permit from the local building official and that requirements vary by city and county. If the visit turns into a replacement in San Jose, CSLB's guidance is to get at least three written bids, and a home improvement down payment should not exceed 10 percent of the price or $1,000, whichever is less.

A single failed part on an otherwise sound furnace is a repair. Replacement makes sense when the heat exchanger is cracked, when major parts are failing one after another, or when you are adding cooling and a heat pump could replace both systems at once.

If the house is cold tonight and someone vulnerable lives there, see the emergency furnace repair page.