Heat Pump Not Heating in San Bruno

Heat Pump Not Heating in San Bruno

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 San Bruno is the sound-rated windows near the airport that seal the house tighter than it was designed for.

Local climate and housing age both matter for a heat pump heating call. San Bruno sits at the foot of San Bruno Mountain and directly under the SFO flight path, and a lot of homes here have upgraded windows for noise rather than for weather, which changes how the house actually breathes. Housing runs from mid-century tracts in Rollingwood and Portola Highlands to newer construction on the hillside. Sound-rated replacement windows are common near the airport corridor, and a house sealed tight against jet noise no longer gets the cross-ventilation it was designed around, which puts more of the comfort and air-quality job on the HVAC system.

In San Bruno, 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. Homes here are often sealed tight with sound-rated windows, which traps more heat and dust around the equipment than the original design assumed. 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. Homes here are often sealed tight with sound-rated windows, which traps more heat and dust around the equipment than the original design assumed.

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. Homes here are often sealed tight with sound-rated windows, which traps more heat and dust around the equipment than the original design assumed.
• 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 San Bruno: common questions

Nearby and related

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

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