Heat Pump Not Heating in Daly City

Heat Pump Not Heating in Daly City

A heat pump that will not heat often comes down to the same reversing valve, only stuck in the other direction, or a defrost cycle that never completes and leaves the outdoor coil iced over. Low refrigerant, a failing outdoor fan motor, or a corroded contactor and capacitor can all shut heating down the same way they would shut down cooling. We check mode, defrost, and charge in that order before opening anything mechanical. The detail that matters in Daly City is the fog that made central air rare here in the first place and the Doelger tract homes built without ducts.

Local climate and housing age both matter for a heat pump heating call. Daly City sits under some of the thickest, most persistent fog in the Bay Area, rolling in off the ocean through the gap near Colma and holding through most summer afternoons. Genuine no-AC-needed days outnumber real heat days most years here. The Westlake district's Doelger-built tract homes from the 1940s and 50s make up a huge share of the city, block after block of nearly identical houses that went up with no ductwork and no central air, because nobody building here in 1955 planned around cooling. Newer construction toward the BART corridor and the hills near San Bruno Mountain breaks that pattern.

In Daly City, we check mode, defrost, and refrigerant charge in that order, because a heat pump that won't heat is rarely one single obvious thing. Whatever the sequence turns up goes on a written estimate, and the $99 diagnostic fee is credited toward the repair.

Common causes

Corroded contactor or capacitor on the outdoor unit. The same electrical parts that fail on an AC condenser fail on a heat pump's outdoor unit. The damp, fog-heavy air here still works its way into loose or aging connections over time, even without direct salt exposure. A failed capacitor or a pitted contactor keeps the outdoor unit from running at all.

Stuck reversing valve. A reversing valve stuck in cooling mode leaves the system unable to produce heat no matter what the thermostat calls for. It is one of the first things we rule in or out.

Low refrigerant from a corroded coil or fitting. A leak drops the charge low enough that the system cannot pull adequate heat from the outdoor air, and a corroded fitting is a common leak point. The damp, fog-heavy air here still works its way into loose or aging connections over time, even without direct salt exposure.

Failed defrost control. In cold, damp conditions the outdoor coil ices over and the system has to periodically defrost it. A failed defrost board or sensor leaves the coil frozen solid, which blocks heat transfer entirely.

Seized or failing outdoor fan motor. Without the outdoor fan moving air across the coil, the system cannot pull heat from the outside air efficiently, and a seized motor is a common, testable failure.

How we diagnose it

• Confirm the thermostat is actually calling for heat and the system is in heat-pump mode, not stuck on emergency or off.
• Read line temperatures at the indoor and outdoor coils to tell whether the reversing valve has actually shifted into heating.
• Meter the capacitor and inspect the contactor for wear. The damp, fog-heavy air here still works its way into loose or aging connections over time, even without direct salt exposure.
• Read refrigerant pressures against the outdoor temperature to spot a low charge before chasing the leak.
• Confirm the defrost board initiates a cycle and the outdoor coil is clear of ice.

$99 diagnostic, credited toward the repair. You get a written quote before any work begins.

Heat Pump Not Heating in Daly City: common questions

Nearby and related

Heat Pump Not Heating near Daly City: South San Francisco · Pacifica · San Bruno .

This is usually a heat pump installation & service in Daly City job. See our heat pump installation & service overview or the Daly City service area.