Heat Pump Not Heating in Milpitas

Heat Pump Not Heating in Milpitas

When a heat pump stops heating, the instinct is to assume the worst. Most of the time it is one part. A heat pump is a refrigeration circuit running backward, and the typical winter failures are a reversing valve stuck in cooling, a defrost fault icing the coil, a slow refrigerant leak, or a tired contactor or capacitor. The compressor and coils usually come through fine.

Milpitas runs warm, with hot summers that lean on these systems for long cooling hours much of the year. High annual runtime wears electrical parts faster, so contactors and run capacitors tend to fail here on a shorter clock than in a cooler town. When that worn unit is asked to make heat on a cold January morning, a marginal capacitor that limped through summer finally can't start the compressor.

Winters themselves are mild and well inside heat pump range, so the climate is not why a Milpitas heat pump quits heating. The housing mixes older stock with newer subdivisions, many of them multi-zone ducted systems. We identify the system, trace the fault to the part, and write the repair and cost on an estimate before any work begins.

Common causes

Failed contactor or capacitor on a high-hour unit. Heavy year-round cooling in Milpitas wears the contactor and run capacitor faster than average. A pitted contactor or a weak capacitor leaves the outdoor unit humming without starting, so no heat moves. We meter both in minutes, and both ride on our truck, so this is usually a same-visit fix.

Reversing valve stuck in cooling. The reversing valve flips the system into heating. When it hangs or its solenoid coil fails, the unit stays in cooling and blows cool air all winter. We read line temperatures across the valve and test the coil. A bad coil is cheap; a stuck valve body is a brazed repair we quote first.

Low refrigerant charge. A slow leak cuts heating capacity until the unit runs long and feels weak. We gauge the system, compare against spec, locate the leak, repair it, and recharge. We seal the leak before recharging; topping off only buys a few months.

Defrost control fault. On cool, damp winter mornings the outdoor coil frosts, and a healthy heat pump clears it on a defrost cycle. A failed sensor or board leaves the coil iced and unable to pull heat. We watch a defrost cycle and confirm the sensor and board are working.

Zone control fault on multi-zone homes. Many newer Milpitas subdivisions run multi-zone ducted systems. When one zone goes cold while another stays warm, the problem is usually a zone damper motor or the zone control board, not the outdoor unit. We check the board and dampers before quoting anything on the condenser.

Aux heat strips not engaging. Ducted heat pumps carry electric backup heat for cold starts and defrost intervals. A failed strip or sequencer leaves the home cold on the worst mornings even while the heat pump runs. We check strip continuity, the sequencer, and the control wiring.

How we diagnose it

• Confirm the thermostat is calling for heat and the outdoor unit responds.
• Meter the contactor and run capacitor first on high-runtime units, since these fail early here.
• Read line temperatures across the reversing valve to confirm the system is in heating mode.
• Gauge the refrigerant charge against spec and leak-check if it reads low.
• On multi-zone homes, check the zone board and damper motors; inspect the outdoor coil for ice and watch a defrost cycle.

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

Heat Pump Not Heating in Milpitas: common questions

Nearby and related

Heat Pump Not Heating near Milpitas: Fremont · Newark .

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