A heat pump moves heat rather than burning fuel to make it. In summer it carries heat out of the house; in winter it pulls heat from the outdoor air and brings it inside. Hayward’s winters, with nights in the 40s rather than deep freezes, suit that well. When a heat pump in Hayward stops heating properly, the cause usually sits in one of three places: the refrigerant circuit and its reversing valve, the defrost system, or the electric backup heat. We repair, maintain and size heat pumps from the bay flats up to the Hayward Hills and Fairview next door.
Heat pump not heating
Cold or room-temperature air in heat mode, or a system that runs and runs without warming the house. First make sure the thermostat is on Heat and set above room temperature, and that the filter is clean. If it still blows cool, these are the usual suspects:
- Reversing valve. This valve switches the system between heating and cooling. If it sticks or its solenoid coil fails, the unit cools when you asked for heat.
- Thermostat setup. After a thermostat swap, a wrong reversing-valve (O/B) setting produces the same symptom. It is a quick fix through thermostat service.
- Low refrigerant. A leak cuts heating output long before the unit stops. The repair is finding and sealing the leak, not just topping it up.
Frozen heat pump
Some frost on the outdoor coil is normal on cold, damp mornings, even with the air above freezing, because the coil runs colder than the air around it. The unit clears it with a defrost cycle: it switches briefly to cooling mode, the outdoor fan stops and steam rises for a few minutes. What is not normal is a coil encased in ice, ice building on the top of the cabinet, or a defrost that never seems to run. The usual causes are a failed defrost control or sensor, a stuck outdoor fan, low refrigerant, or water dripping onto the unit from a gutter. Do not chip at the ice; the fins and tubes bend easily. If the system has backup heat and you need warmth, switch the thermostat to EM HEAT and call.
AUX heat running constantly
Most ducted heat pumps have electric heat strips as backup. The thermostat shows AUX when they run alongside the heat pump, which is expected during defrost and on the coldest nights. If AUX is lit most of the time, your electric bill climbs, and the heat pump itself is usually the reason: low charge, a weak compressor, a defrost fault or ducts losing heat. A thermostat that calls for backup heat too early does the same. EM HEAT is different: the heat pump is off and only the strips run. Use it only when the heat pump has failed.
Sizing for Hayward’s microclimates
Hayward runs from flat land by the bay up into the Hayward Hills, and the same house behaves differently in each:
| Where the house sits | What changes | What sizing has to cover |
|---|---|---|
| Bay flats | Mild summers, winter nights in the 40s | Modest heating and cooling loads; oversizing is the common mistake |
| Hayward Hills and Fairview | Cooler nights, more wind, often more glass | More heating capacity; wind exposure and window area in the load |
| Any home, on heat-wave days | Long afternoons of full-load cooling | Enough cooling for the hottest stretch without short-cycling in mild weather |
A heat pump’s heating output falls as the outdoor temperature drops, just as the house starts losing heat faster. A unit sized only for summer cooling can come up short in a hill home on a windy January night, and the backup strips then make up the difference at a higher running cost. Variable-speed (inverter) heat pumps cover a wide range of loads smoothly. We size from a load calculation for your house, for heating and for cooling, never from the old unit’s label.
Switching from a furnace
Many Hayward homes built between the 1950s and the 1970s still run an older gas furnace. Replacing a tired furnace and AC with a heat pump is a common upgrade, and two checks come first:
- The electrical panel. Older ranch homes may have a small panel; a heat pump and its backup heat need their own circuits and enough spare capacity.
- The ducts. A heat pump delivers heat at a lower supply temperature than a gas furnace, so it relies on more airflow. Attic or slab ducts sized for the furnace may need work first.
If you would rather keep the gas furnace, a dual-fuel setup lets the heat pump do most of the heating and hands over to the furnace on the coldest nights. Our furnace installation page covers that side.
Twice-a-year care
- Keep the outdoor unit clear of plants, stored items and leaves, with open space on every side.
- Change the filter monthly during heavy use.
- Book professional maintenance twice a year through HVAC maintenance, before winter and before summer.
- Watch the defrost: a few minutes of steam on a cold morning is fine; ice that stays is a service call.
Repairs carry our warranty and use manufacturer-recommended parts, and you get a flat price after diagnosis, before any work. We service all major brands, including Carrier, Trane, Daikin, Mitsubishi Electric and Fujitsu. Ductless heat pumps have their own page: ductless mini-split service.