How this shows up in Point Loma Salt air off the water is the defining factor here. It corrodes outdoor condenser coils and cabinets faster than anywhere inland, and standard equipment often fails in six to nine years instead of twelve to fifteen. Marine-layer mornings hold humidity into early afternoon, and the cooling load stays mild most of the year.
The hillside blocks in Roseville, La Playa, and the Sunset Cliffs edge sit in direct salt-air exposure where condensers can fail in six to nine years without corrosion protection, so we spec coastal coils and stainless hardware. The 1950s tract on the Point Loma mesa runs original ductwork due for renewal, and the light marine cooling load makes heat pumps a strong fit throughout.
What causes a furnace that won’t heat
Failed igniter or flame sensor A cracked hot-surface igniter or a dirty flame sensor is the most common reason a furnace tries to start, clicks, and shuts back down without heating.
Thermostat set or wired wrong A thermostat left in cool mode, a dead battery, or a setting below room temperature stops the heating call before the furnace ever tries.
Tripped safety or limit switch A safety switch trips to protect the furnace from overheating or a blocked flue, and it needs a reset and a cause check rather than just a restart.
Clogged air filter A filter packed with a year of dust restricts airflow enough that the furnace overheats and shuts itself off through its own safety switch.
Gas valve or gas supply issue A closed gas valve, a tripped gas shutoff, or a valve that failed to open keeps the burners from ever lighting.
Pilot light out on an older furnace Older standing-pilot furnaces lose their flame to a draft or a worn thermocouple, and the whole system stays cold until the pilot is relit.
Failed blower motor A dead or seizing blower motor means the burners may light but the warm air never makes it into the ducts and the house.
Tripped breaker or blown fuse Furnaces run on a dedicated circuit, and a tripped breaker or blown control-board fuse kills the whole unit with no warning.
When to stop and call a tech
Call a tech if you smell gas near the furnace, if the unit repeatedly tries to start and shuts off, or if a breaker trips again right after being reset. Any of those point to a safety switch doing its job, and forcing a restart without a diagnosis risks a bigger failure or a real safety issue.
What it costs to get a furnace heating again
In Point Loma$89 to $2,200
A diagnostic runs $89 and is credited to the repair. An igniter, flame sensor cleaning, or thermostat fix typically lands in the low hundreds. A failed blower motor or gas valve replacement is the higher end of the range, and on an older furnace it can be where the repair-or-replace conversation starts.