A heat pump moves heat instead of making it: in summer it carries heat out of the house like an air conditioner, and in winter a reversing valve sends the refrigerant the other way and pulls heat in from the outdoor air. In Novato, San Rafael, San Anselmo, Larkspur and Sausalito, where winters are cool and damp rather than freezing, that works well and gives many older homes cooling for the first time. We repair, maintain and install heat pumps, both ducted systems and ductless mini-splits.
Normal heat pump behavior, and what is not
Several things worry new heat pump owners that are completely normal:
- Steam from the outdoor unit on cold, damp mornings, during a defrost cycle.
- A short pause in the heat and a whoosh when the reversing valve switches into or out of defrost.
- Air that feels warm rather than hot at the registers.
- Long run times. A heat pump is designed to run steadily, not in short bursts.
These are signs of a fault:
- A solid block of ice on the outdoor coil that does not clear after a defrost.
- Cold air in heating mode, or warm air in cooling mode, for more than a few minutes.
- The outdoor fan running while the compressor stays silent, or the reverse.
- Backup heat running constantly, often visible as a jump in the electricity bill.
Common heat pump repairs
| Problem | What usually causes it |
|---|---|
| Heat pump not heating | Reversing valve stuck, low refrigerant, failed defrost control, thermostat wired for the wrong valve setting |
| Heat pump not cooling | The same valve or charge problems, a dirty coil or a failed capacitor |
| Defrost cycle problems | Faulty defrost board, temperature sensor or outdoor coil sensor |
| Frost building up on the outdoor unit | Defrost failure, low airflow across the coil, low charge |
| Refrigerant issues | Leaks at fittings, the coils or a rubbed line set |
| Compressor problems | Failed start or run capacitor, contactor, overheating, or a worn compressor |
| Reversing valve failure | Stuck valve or failed solenoid coil |
| Poor efficiency | Dirty coils, low charge, backup heat running too often |
Because a heat pump does two jobs, we always finish a repair by running it in heating and in cooling mode. A fault that hides in one mode often shows in the other.
How a heat pump diagnosis works
We start with a system evaluation: what the thermostat is asking for, how the system responds, and whether backup heat is involved. Then we check the refrigerant pressures and temperatures, test the electrical components - the capacitors, the contactor, the defrost board and the reversing valve solenoid - and look at airflow and the indoor coil. Our technicians are EPA-certified to handle refrigerant, and a low charge always means finding the leak, not just refilling. You get the cause and an itemized price before any repair begins.
Maintenance for a system that never rests
A furnace rests all summer and an air conditioner all winter. A heat pump works in both seasons, so it wears faster and benefits from two checks a year. A heat pump tune-up includes cleaning the outdoor coil, checking the defrost controls and sensors, testing capacitors and contactors, measuring the refrigerant charge, checking the backup heat and clearing the condensate drain. Outdoor units near the water in Sausalito and on the bay side of San Rafael and Larkspur collect salt on the coil, and a gentle rinse between visits helps. See HVAC maintenance for our plans.
Installing a heat pump
The most common heat pump project in Marin replaces an aging gas furnace and adds cooling in one step. Before we recommend one, we look at:
- Sizing from a load calculation, for heating and cooling.
- The ducts - whether they can carry the airflow a heat pump needs, or whether a ductless layout fits better.
- The electrical panel - a heat pump and its backup heat may need a new circuit or more panel capacity.
- Outdoor placement - clear space for airflow, a spot where defrost water can drain away, and a location on a hillside lot that the line set can reach.
- The thermostat, which must be compatible with heat pumps; see thermostat installation.
Heat pumps from all major brands carry the manufacturer’s warranty, and our installation carries a labor warranty. Local pages: heat pump services in Novato and in Larkspur.