Heat Pump Not Cooling in Piedmont, CA

Heat Pump Not Cooling in Piedmont

A heat pump runs the same refrigeration cycle as an air conditioner, with a reversing valve added so one unit handles both heating and cooling. When a Piedmont heat pump runs but stops cooling, we diagnose it like a failed AC and then check that reversing valve, the part a cooling-only system never has.

Piedmont sits up in the Oakland hills, mild and marine-influenced, where summers rarely top the mid-80s. Cooling was historically an afterthought here, but more owners of these older Tudor and Mediterranean estates have added it, and a mild climate is exactly where a heat pump makes sense for both heat and AC. Because these houses are large, multi-story, and often zoned, a cooling failure can read differently floor to floor, with the top floor staying hot while the system seems to be running.

The reassuring part is that a heat pump that runs but will not cool almost always has one failed part, not a dead system. On a zoned estate system, the work is often isolating whether the failure is in the shared equipment or in one zone's damper or controls. We find it and put the fix and the price on a written estimate before any work begins.

Common causes

Reversing valve stuck in heat mode. This is the failure a straight AC cannot have. The valve that flips the system between heating and cooling can stick, or its solenoid coil can fail, leaving the unit running in heat while you call for cool. We confirm it by reading line temperatures through a mode change. A failed coil is a smaller repair; a stuck or leaking valve body is a larger one, and we show you which it is.

Zoning damper or zone-control failure. On these multi-story floor plans we almost always zone the system, and a stuck damper or a failed zone board can leave one floor with no cooling while the equipment runs fine for the rest of the house. This failure mimics a system problem but is isolated to a zone. We test the dampers and the zone controller to separate a zoning fault from an equipment fault.

Refrigerant leak or low charge. Low refrigerant from a slow leak makes the system run constantly and barely cool. On retrofits routed through finished plaster-walled estate homes, leaks often sit at line-set joints. We pressure-test, find the leak with detection or dye, repair it, and weigh in the correct charge rather than topping off, which only delays the next failure.

Dirty outdoor coil. A condenser coil packed with debris cannot reject heat, so the house does not cool even with the unit running. It is the least costly item on the list. We clear the airflow path, wash the coil, and recheck pressures to confirm recovery before moving deeper into diagnosis.

Failed capacitor or contactor. A weak run capacitor leaves the compressor or fan straining to start, and a pitted contactor fails to power the outdoor unit, so it runs without cooling. We carry both and meter the capacitor instead of judging by appearance.

Frozen indoor coil from low airflow. A dirty filter or a weak blower starves the indoor coil until it ices over, and ice does not cool the air moving past it. On larger zoned systems, undersized original ductwork can also restrict airflow enough to freeze a coil. We thaw it, find the restriction, and fix the cause so it does not re-freeze.

How we diagnose it

Confirm the thermostat is set for cooling and sending the correct reversing-valve signal before chasing equipment.
On zoned systems, test the dampers and zone controller to determine whether the no-cooling is system-wide or isolated to one floor.
Read line temperatures and pressures through a mode change to verify the reversing valve is moving into cooling.
Inspect the outdoor coil and meter the capacitor and contactor at the condenser.
Check the indoor coil and filter for ice and airflow restriction, including undersized original ductwork that can starve the coil.

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

Heat Pump Not Cooling in Piedmont: common questions

Do you cover Piedmont, and how fast can you respond?

We are based in San Ramon and work Piedmont and the surrounding inner East Bay estate neighborhoods. Same-day is best effort, not a guarantee, but a no-cooling call gets priority. If your system is zoned, tell us when you book so we arrive ready to test the zone controls along with the equipment.

Only my top floor stays hot. Is the whole heat pump failing?

Usually not. In a multi-story Piedmont home, one floor staying hot while the system runs typically points to a zoning damper or zone-control fault, not the heat pump itself. We test the dampers and controller to confirm. A true equipment failure, like a low charge or a stuck reversing valve, affects every zone, and we diagnose accordingly.

It is mild up here. Is paying to fix the cooling worth it on an older estate system?

The same heat pump heats the house all winter, so a stuck valve or low charge hurts the heating side too, which makes the repair worth understanding even in a mild summer. We will tell you honestly whether you are looking at a small part or a larger issue, and your repair carries a one-year warranty so you know where you stand.

Nearby and related

Heat Pump Not Cooling near Piedmont: Oakland · Berkeley · Alameda .

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