Heat Pump Not Heating in Lafayette

Heat Pump Not Heating in Lafayette

A heat pump that stops heating in Lafayette is almost always one failed part, not a dead system. The Diablo Valley is mild, but a cold overnight is exactly when a marginal part gives up. Even then, the equipment is operating within its range, and the fix is usually a component, not a replacement.

Lafayette's terrain adds its own complications. Many outdoor units sit on steep, shaded, tight lots where the coil stays cold and damp, which makes the defrost system work harder and exposes a weak defrost board or sensor faster than on a flat sunny lot. Access matters too: the line runs and condenser placement we scope at the estimate are the same ones that make a repair straightforward instead of awkward.

Some Lafayette homes run ductless mini-splits, retrofitted onto older hillside houses where ducts were poor or never existed. Mini-splits fail to heat for their own reasons: one zone's outdoor unit, a clogged or frosted coil, a communication fault between heads and the condenser. We diagnose ducted and ductless heat pumps both, and the finding goes on a written estimate.

Common causes

Outdoor coil iced over from a defrost fault. On shaded, damp hillside lots the outdoor coil frosts readily, and if the defrost board or sensor fails the coil ices solid and the unit can no longer pull heat from the air. We run a defrost cycle, test the sensor, and replace the board if it is not clearing frost on schedule. We also check that the unit has the clearance and drainage the lot allows.

Reversing valve stuck. A stuck reversing valve or failed solenoid coil keeps the heat pump in cooling, so it blows cold in winter. We test the coil and confirm the valve shifts on a mode change. A coil is a part swap; a seized valve is a refrigerant-side repair, and we identify which before quoting.

Ductless mini-split zone fault. On a ductless retrofit, a single zone can stop heating from a communication error between the head and condenser, a frosted indoor or outdoor coil, or a failed outdoor board. We read the unit's error codes, check the line-set and drain, and isolate the failing component rather than condemning the whole system.

Low refrigerant charge. A heat pump low on charge cannot move enough heat and runs long without warming the house. On hillside homes a line set routed through framing can develop a slow leak. We gauge the system, read subcooling and superheat, and trace the leak instead of topping off.

Capacitor or contactor failure. A weak capacitor or pitted contactor stops the compressor from starting, leaving the blower to move unheated air. These are common wear items on the older outdoor units we see around Lafayette. We measure against rating and replace from truck stock.

Backup heat not engaging on cold nights. On the upper-hillside homes that catch the coldest overnight lows, the electric backup strips matter most, and a failed sequencer or relay leaves cold air on exactly the coldest night. We confirm the strips draw current on a call and that the control stages them at the right outdoor temperature.

How we diagnose it

• Run a defrost cycle and inspect the outdoor coil for ice, then test the defrost board and sensor; confirm the unit has adequate clearance on the hillside lot.
• Confirm the reversing valve shifts into heating on a call and the compressor runs.
• On ductless systems, read error codes and check each zone's coil, line set, and communication to the condenser.
• Gauge refrigerant charge against subcooling and superheat targets and trace any leak.
• Measure capacitors, inspect the contactor, and verify backup heat strips stage in on cold nights.

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

Heat Pump Not Heating in Lafayette: common questions

Nearby and related

Heat Pump Not Heating near Lafayette: Orinda · Moraga · Walnut Creek · Alamo .

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