Heat Pump Not Cooling in San Ramon

Heat Pump Not Cooling in San Ramon

San Ramon sits in the Tri-Valley, where July and August routinely break 95 and cooling is the bigger workload of the year. A heat pump that won't cool here gets noticed immediately, because the house heats up fast and there's no cool coastal break to hide the problem. This is our home city, so it's also the call we get to quickest.

A heat pump runs the same cooling cycle as an air conditioner. It moves heat out through the outdoor coil, and a reversing valve switches the refrigerant flow between heating and cooling. Get warm air on a cool call and the fault is usually narrow. A valve that won't shift, a charge gone low on a leak, a fouled outdoor coil, a dead capacitor, or an indoor coil frozen on starved airflow. The compressor and the rest of the system are usually fine.

Much of San Ramon is 1980s and 90s tract housing in Windemere, Twin Creeks, and the Crow Canyon corridor, where original AC condensers and aging heat pumps are at the point where capacitors and valves start failing. The newer Gale Ranch and Dougherty Valley systems are usually in better shape but more complex to diagnose. Either way, a no-cooling call gets diagnosed like an AC, by reading pressures and confirming the valve shifts.

Common causes

Reversing valve stuck in heat. A valve that won't shift into cooling leaves the unit running in heat on a cool call. We energize cooling and read line temperatures across the valve to confirm whether it physically flips. A stuck solenoid or failed valve body is identified at the unit and priced on the estimate.

Low refrigerant from a leak. In San Ramon's summer heat a low charge means the unit runs nonstop and never cools the house. We read superheat and subcooling, then locate the leak with electronic detection instead of just recharging. On a confirmed leak we lay out repair cost against the system's age and remaining life.

Failed run capacitor. On the 80s and 90s equipment common here, the run capacitor is the most frequent summer failure. When it goes, the compressor or condenser fan can't start and you get warm air. We test it against rated microfarads and replace from stock, almost always the same visit.

Dirty outdoor coil. Tri-Valley dust and yard debris coat the outdoor coil over the years and cut its ability to reject heat. In 95-degree weather that's the difference between cooling and not. We wash the coil and re-read pressures to confirm capacity returned.

Frozen indoor coil from low airflow. A clogged filter or weak blower starves the indoor coil until it ices and cooling stops completely. We check filter, blower, and coil, thaw any ice, fix the airflow restriction, and verify charge so it doesn't refreeze.

Contactor failure. A pitted or burned contactor can keep the outdoor unit from energizing on a cool call. We inspect and test it under load and replace it from stock when the contacts are worn.

How we diagnose it

• Confirm cool mode and correct reversing-valve (O/B) wiring at the thermostat.
• Read pressures and calculate superheat and subcooling to separate low charge from a valve or airflow fault.
• Verify the reversing valve shifts into cooling by reading temperatures across the valve.
• Test capacitor and contactor electrically and inspect both coils for fouling and ice.
• Write the confirmed fault and repair cost on an estimate, with repair-versus-replace numbers on older condensers.

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

Heat Pump Not Cooling in San Ramon: common questions

Nearby and related

Heat Pump Not Cooling near San Ramon: Danville · Alamo · Dublin · Pleasanton .

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