Heat Pump Not Cooling in Woodside
Woodside's hillside and canyon locations keep summers mild most years, so a heat pump that quietly stops cooling can go unnoticed for a week or two before anyone actually feels it. By the time someone calls, it's usually one of two things: a cooling-side part failed, or the system is stuck in heating mode. A heat pump cools by reversing its refrigerant flow, so heating and cooling run through the same loop. When it heats fine but won't cool, the cooling-specific hardware is almost always where the fault lives.
Most Woodside estates run independent systems for the main house, the guest house, and often the pool house, so the symptom usually shows up in just one part of the property. That narrows the search right away. One building going warm while the others stay cool tells us the problem is local to that condenser and air handler, not something affecting the whole property, and we can isolate the affected system instead of chasing everything.
This is rarely a dead unit. A stuck reversing valve, a failed capacitor, or a slow refrigerant leak are single-component faults, each with a defined fix we can put on a written estimate before any work starts.
Common causes
Reversing valve stuck in heat mode. The reversing valve switches a heat pump between heating and cooling. If it sticks, or the solenoid fails, the unit keeps running but blows warm air instead of cooling. We check the valve's position electrically and by line temperature, then replace the solenoid or the valve depending on what tests bad.
Low refrigerant from a leak. If the charge has dropped, the system runs but can't pull heat out of the building, so you get weak, lukewarm air. We don't just top it off. We find the leak first, usually at a flare fitting, a service valve, or the coil, using electronic detection or a nitrogen pressure test, then repair, evacuate, and recharge to spec. On the long line-set runs common between a main house and a detached pool house or guest house, fittings and joints are the usual culprits.
Dirty or blocked outdoor coil. These wooded, redwood-canyon lots shed a steady load of leaf litter and pollen onto outdoor coils. A clogged coil can't reject heat, head pressure climbs, and cooling capacity drops off. We clean the coil, clear the clearance around it, and recheck pressures. It's one of the cheaper fixes and easy to miss if nobody looks at the outdoor unit directly.
Failed capacitor or contactor. The run capacitor starts the compressor and fan, and the contactor switches power to them. When either fails, the unit may hum, trip, or run the fan without the compressor, so air moves but never cools. We test both with a meter and carry common sizes on the truck, so this is often a repair using a part we usually stock.
Frozen indoor coil from low airflow. A dirty filter, a weakening blower, or a closed return starves the indoor coil of airflow and it ices over. Once frozen, almost no cold air reaches the rooms. We thaw it, find out why airflow dropped, and fix that. On a zoned system across a large main house, a stuck damper can choke airflow to one coil, which is worth checking specifically.
Thermostat or zoning control in the wrong mode. With separate thermostats for the main house, guest house, and pool house, it's easy for one to sit in heat mode or for a control board to drift. Each thermostat's mode and call get verified, we confirm the board is sending the cooling signal and energizing the reversing valve, and we rule out a control fault before we touch the refrigerant side.
How we diagnose it
- Confirm which building or system is affected, and verify that thermostat is actually calling for cooling, not stuck in heat or auto.
- We check the reversing valve's position from line temperature and energize its solenoid to confirm it shifts properly on a cooling call.
- Suction and head pressures get read against the outdoor temperature to see if the charge is low or the coil is struggling to reject heat.
- Test the capacitor and contactor, and inspect the outdoor coil for leaf litter and debris common on these wooded lots.
- Inspect the indoor coil and filter for ice and airflow restriction, and check zoning dampers for the affected building or wing.
$99 diagnostic, credited toward the repair. You get a written quote before any work begins.
Heat Pump Not Cooling in Woodside: common questions
You're based in San Ramon. How do you actually cover Woodside?
Our summers stay mild up in the trees. Is a heat pump that won't cool even worth fixing right away?
It heats fine in winter but won't cool in summer. What does that tell you?
Nearby and related
Heat Pump Not Cooling near Woodside: Portola Valley · Hillsborough · Menlo Park .
This is usually a heat pump installation & service in Woodside job. See our heat pump installation & service overview or the Woodside service area.
Heat Pump Not Cooling in Woodside
Repairs start with a $99 diagnostic, credited toward the fix. Replacing a system? The on-site assessment visit is free. Same-day written findings either way.
Bay Area · 7am–7pm · 7 days · no overtime charges