Evergreen sits in the East San Jose foothills, and many of its homes are tract houses that still have the furnace and air conditioner the builder put in. That builder-grade equipment is now reaching replacement age. Summers here are warm, and winter nights are cool enough to keep the furnace busy every morning and evening. For HVAC service in Evergreen, San Jose, that means three things: furnace repair, yearly furnace maintenance, and choosing the right size when an original system is finally replaced.
Furnace problems on original equipment
Older furnaces fail in familiar ways, and most of these are single-part repairs rather than a reason to replace.
| What you notice | Likely cause | What it usually takes |
|---|---|---|
| Burners light, then shut off after a few seconds | Dirty or worn flame sensor | Cleaning or replacing the sensor |
| Inducer fan runs, but nothing lights | Cracked hot-surface igniter or a pressure switch fault | Igniter replacement, or a venting and switch check |
| Starts and stops every few minutes | Clogged filter tripping the high-limit switch, or an oversized furnace | Filter and airflow fix, limit switch test |
| Air from the vents is cool | Thermostat fan set to On, or burners shut down by a limit or ignition fault | Fan back to Auto, or diagnosis of the shutdown |
| Squeal or rumble from the cabinet | Worn blower or inducer motor bearings | Motor replacement |
| Nothing happens at all | Tripped breaker, open door switch, blown control fuse or thermostat fault | Electrical diagnosis |
Step-by-step help is on furnace not igniting and furnace short cycling; repair options are on our furnace repair page.
Safe checks before you call
- Set the thermostat to Heat, a few degrees above room temperature, and replace its batteries if it uses them.
- Check the filter. A clogged one is a frequent reason a furnace shuts itself off.
- Make sure the switch near the furnace, which looks like a light switch, is on and the breaker has not tripped.
- Check that the furnace door is fully closed: a safety switch keeps the furnace off while the panel is loose.
- If the furnace has a small window with a blinking light, write down the pattern. It is a fault code.
Do not keep resetting a furnace that will not light. If you smell gas, leave the house and call the gas company or 911 from outside. If a carbon monoxide alarm sounds, get everyone out first.
Maintenance before the cool nights
A yearly furnace tune-up before the heating season finds weak parts before the first cold week puts them to work. It covers the filter, flame sensor and igniter, burners, the visible part of the heat exchanger, venting and the inducer, the pressure and limit switches, the blower and its capacitor, and the thermostat. See furnace maintenance. The air conditioner shares the furnace blower and ducts, so a maintenance plan that checks cooling in spring and heating in fall is often simpler than booking each visit.
Replacing builder-grade equipment: size it, don’t copy it
When an original furnace or AC needs replacing, the easy move is to install the same size again. That size is not proof it was right, and the house may have changed since: new windows, added insulation, a converted garage or an extra room. Correct sizing starts with a room-by-room load calculation.
- An oversized furnace heats in short bursts, cycles often and leaves some rooms cold while others overheat. An oversized AC does the same in summer.
- An undersized system runs nonstop on the coldest nights and the warmest afternoons.
- Two-stage and variable-speed equipment runs at low output most of the time, which keeps temperatures steadier from room to room.
If the furnace and AC are replaced at different times, the new outdoor unit still needs a matching indoor coil, and the furnace blower has to move the right amount of air for it. Some owners switch to a heat pump at this point, which handles both heating and cooling. Estimates for new systems are free; furnace installation explains how a replacement works.
Summer still counts
Evergreen summers are warm, and the air conditioner uses the same blower, ducts and filter as the furnace. A weak blower capacitor or a clogged filter shows up as poor heat in winter and poor cooling in summer, so a fault found in one season is worth fixing before the next. For no-cooling calls, see AC repair.
Booking
Same-day service is available for most calls received before noon, and urgent no-heat calls are taken 24/7. For repairs a diagnostic fee applies and is waived if you go ahead, and you approve the price before work starts. Typical furnace repair prices are in our furnace repair cost guide.