Heat Pump Not Heating in Moraga, CA | Bay Area HVAC Service

Heat Pump Not Heating in Moraga

A heat pump that won't make heat is seldom a dead system. It is a refrigeration loop run in reverse, and the usual culprits are single parts: a reversing valve stuck in cooling, a defrost control leaving the coil iced, a low refrigerant charge, or a contactor that won't close. The compressor and coils, the parts that would tip the decision toward replacement, almost always survive.

Moraga sits in a quiet valley between Lafayette and Orinda, with cool morning fog giving way to warm afternoon sun. That daily swing is part of why heat pumps run efficiently here, but the damp, foggy mornings are also when an outdoor coil frosts. A healthy heat pump clears that frost on a defrost cycle. When the cycle fails, the coil ices solid and stops absorbing heat, which is one of the more common winter no-heat calls we get from Moraga.

Winters are mild and well inside heat pump range, so the valley climate is not the reason a unit quits heating. Many Moraga homes are older single-story houses on larger hillside lots, often with conventional ducted heat pumps and aging components. We trace the fault to the part, factor in hillside access when a part needs replacing, and put the repair and cost on a written estimate before we start.

Common causes

Outdoor coil iced from a defrost fault. Foggy Moraga mornings frost the outdoor coil, and a working heat pump melts it off on a timed defrost cycle. A bad defrost sensor or control board skips that cycle, the coil glazes over, and an iced coil cannot pull heat from the air. We watch a defrost cycle, check sensor resistance, and confirm the board terminates correctly before replacing anything.

Reversing valve stuck in cooling. When the reversing valve hangs or its solenoid coil fails, the unit keeps running in cooling and blows cool air all winter. We read temperatures across the valve and test the coil voltage. A failed coil is inexpensive; a stuck valve body is a brazed repair, and we tell you which it is before quoting.

Low refrigerant charge. A slow leak drops heating capacity over a couple of seasons until the unit runs long and makes weak heat, sometimes icing the coil. We gauge the system against spec, find the leak, repair it, and recharge. We seal the leak first; topping off only delays the same call.

Failed contactor or capacitor. A pitted contactor or weak run capacitor leaves the outdoor unit silent or humming, so the compressor never starts and no heat moves. On aging single-story systems these are common failures, and both are fast meter checks with parts on the truck.

Aux heat strips not engaging. Ducted heat pumps carry electric backup heat for cold starts and for the minutes the unit spends in defrost. A failed strip or sequencer leaves the home cold on damp mornings even while the heat pump runs. We check strip continuity, the sequencer, and the control wiring that calls for backup.

Aging components on an older system. Many Moraga homes run heat pumps that are getting on in years, where multiple small parts start failing together. We diagnose the immediate no-heat cause, then give you an honest read on whether the rest of the system has the life left to justify the repair versus planning a replacement.

How we diagnose it

Inspect the outdoor coil for ice and watch a full defrost cycle, then check the defrost sensor and board.
Confirm the thermostat is calling for heat and the outdoor unit responds.
Read line temperatures across the reversing valve to confirm the system is in heating mode.
Gauge the refrigerant charge against spec and leak-check if it reads low.
Meter the contactor, capacitor, and aux heat strips, and assess overall system age on older units.

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

Heat Pump Not Heating in Moraga: common questions

Do you come out to Moraga, including the hillside lots?

Yes. We are based in San Ramon and cover Moraga, Orinda, and Lafayette regularly. Hillside condenser access and line routing are routine for us. Mention the access situation when you call (925) 999-4095 and we will plan the visit around it.

Why does my Moraga heat pump ice up on foggy mornings?

Some frost on the outdoor coil during cool, damp mornings is normal, and a healthy unit clears it automatically with a short defrost cycle. The valley fog just makes frost more likely here. If the coil stays caked in ice and the house goes cold, the defrost cycle has failed, which is a sensor or board repair, not the end of the system.

My heat pump is well over 15 years old and stopped heating. Repair or replace?

We diagnose the immediate cause first. A part like a contactor or reversing valve can often be repaired affordably. But on an older unit we will tell you honestly whether one more repair makes sense or whether you are better off planning a replacement. New installs carry a 10-year parts and labor warranty; repairs carry a one-year warranty.

Nearby and related

Heat Pump Not Heating near Moraga: Orinda · Lafayette .

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