Heat Pump Not Heating in Alamo

Heat Pump Not Heating in Alamo

A lot of Alamo homes run more than one heat pump to cover the square footage, so when one zone stops heating the rest of the house masks it for a while. By the time someone calls us, half the house has been cold for days. That is the most common version of this call here: a single zone or a single outdoor unit that quit, not a whole-house failure.

A heat pump heats by running its refrigerant cycle in reverse, pulling heat out of the outdoor air and pushing it inside. When it stops heating, the problem is almost always one component in that loop. It might be the reversing valve that flips the cycle. It might be the defrost control, a low refrigerant charge, or the backup electric heat strips that carry the load while the unit defrosts. Any of those leaves you with the air handler running and cold air coming out.

Winters here are mild, and these units are rated for far colder than the Bay Area gives them. So when a heat pump won't heat in Alamo, it is a part problem, not the weather beating the equipment. We diagnose the failed component and put the fix on a written estimate before any work starts.

Common causes

Stuck reversing valve. The reversing valve is what switches the unit between cooling and heating. When the solenoid sticks or the valve fails to fully shift, the unit keeps running in cooling mode in January and blows cold. We confirm it by reading suction and discharge line temperatures and listening for the valve shift on a call for heat. A stuck valve usually means replacing the valve and recharging.

Backup heat strips not engaging. On larger Alamo systems the electric heat strips carry the load during defrost and on the coldest mornings. A tripped sequencer, blown fuse on the heat kit, or failed relay leaves the air handler blowing room-temperature air. We check the heat kit for continuity and verify the thermostat is calling for aux heat, then replace the failed sequencer or element.

Low refrigerant charge. A heat pump short on refrigerant loses heating capacity first, often before it shows cooling problems in summer. The cause is a leak, not normal consumption. We pressure-test, find the leak with electronic detection or dye, repair it, then weigh in a correct charge. We do not simply top it off and leave.

Defrost control fault. In cold damp mornings the outdoor coil frosts and the defrost board is supposed to clear it. A failed defrost sensor or board lets ice build until the unit can no longer pull heat from outside air. We test the defrost cycle, check the coil sensor reading against actual coil temperature, and replace the sensor or board.

Failed contactor or capacitor. If the outdoor unit is dead silent on a heat call, the run capacitor or contactor in that condenser has often failed. The air handler still runs, so the house feels like the heat is on, but no heat is being moved. We meter the capacitor and check the contactor for pitting, both stocked parts.

Zone damper or control board on multi-zone systems. On Alamo dual-zone and dual-system homes a stuck damper or drifting zone board can starve one area of heated air while another roasts. We run the zone panel diagnostics in sequence rather than swapping boards blindly, because most of these turn out to be a stuck actuator or a wiring fault, not the board.

How we diagnose it

• Confirm the thermostat is calling for heat and the reversing valve is actually shifting, by reading line temperatures at the condenser.
• Verify the outdoor unit energizes on a heat call: contactor pulls in, compressor and fan run, capacitor reads in spec.
• Check the defrost cycle and coil sensor, and inspect the outdoor coil for ice buildup.
• Test the backup heat strips and sequencers, since on larger systems they carry real load during defrost.
• On multi-zone homes, run the zone panel and damper diagnostics to isolate which zone or system actually failed.

$75 diagnostic, credited toward any repair over $200. You get a written quote before any work begins.

Heat Pump Not Heating in Alamo: common questions

Nearby and related

Heat Pump Not Heating near Alamo: Danville · Blackhawk · Lafayette · Walnut Creek .

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