The short answer
Heating repair covers both systems that stop working and systems that run but leave rooms cold or uneven. The usual culprits are ignition or electrical faults on one side, and duct leaks, airflow restrictions or thermostat issues on the other.
Not every heating problem is a dead system. Some of the most common calls we get from Cupertino are about heat that works, technically, but does not make the house comfortable: a family room that stays chilly, a bedroom that gets stuffy, air that feels dry and dusty, or a thermostat that seems to have its own opinions. Those complaints have causes just as specific as a failed igniter. ReliableAir HVAC Services repairs furnaces, heat pumps and ductless heating systems in 95014, about eight miles southwest of San Jose. This page covers both kinds of problem, the no-heat emergency and the slow comfort complaint, and explains how we track each one back to its source.
When there is no heat at all
Start with the thermostat. Confirm it is set to Heat, the setpoint is above room temperature, and the display is working. Check the breaker for the furnace or air handler and the service switch, which often looks like a light switch on or near the unit. Replace the filter if it is dirty.
If heat still does not come on, the fault is usually inside the equipment. On gas furnaces, that tends to be the igniter, flame sensor, pressure switch, inducer motor or control board. On heat pumps, look to the reversing valve, defrost controls, capacitors or refrigerant charge. These need testing on site, and we bring common replacement parts on the truck.
When some rooms stay cold
Uneven heat is rarely the furnace's fault. Heat travels through ducts, and ducts in older Cupertino homes have had decades to sag, separate and leak. A disconnected run in the attic can send a bedroom's heat straight into the rafters. Additions and remodels often tapped into existing ducts that were never sized for the extra rooms.
We measure airflow at the registers, inspect accessible duct runs, and check the return side. Fixes range from reconnecting and sealing a few joints to adding a return or rebalancing dampers. For a room that is simply too far from the system, a ductless head can be the practical answer.
When the air feels dry, dusty or stale
Winter in the Santa Clara Valley is mild and damp outdoors, but heated indoor air can still feel dry. Leaky return ducts make it worse by pulling in dusty attic or crawlspace air. A filter that is too restrictive, or one that does not fit its slot, can let dust bypass it entirely.
During a repair visit we look for gaps around the filter rack, open return joints and dirty blower wheels. Sealing the return side often improves both comfort and cleanliness more than any accessory.
When the thermostat seems wrong
A thermostat mounted on a sunny wall or near a kitchen will read warm and shut the heat off early. One configured for a gas furnace but connected to a heat pump will behave erratically. Loose low-voltage wiring can cause random shutdowns. We check placement, wiring and configuration, and we confirm the thermostat is set up for your actual equipment.
- Heat pump systems need the correct reversing valve and auxiliary heat settings
- Two-stage furnaces need staging set so the low fire actually gets used
- Smart thermostats sometimes need a common wire to stay powered
- Zoned systems need each zone sensor and damper tested
Safety comes before comfort
If you ever smell gas, leave the house and call your gas utility from outside. If a carbon monoxide alarm sounds, get everyone out and call for emergency help. On gas furnaces, every repair visit includes a look at venting, flame quality and safety switches.
If your heating equipment is aging, keep in mind that Bay Area Air District rules do not require replacing working equipment. They apply only when a furnace or water heater fails or is replaced. Repair remains a reasonable path while it makes sense, and we will tell you plainly when it stops making sense.
More services in Cupertino
- AC Repair in Cupertino
- Heat Pump Installation in Cupertino
- AC Installation in Cupertino
- Furnace Repair in Cupertino