Heat Pump Not Cooling in Concord

Heat Pump Not Cooling in Concord

A heat pump cools the same way a straight AC does. It pulls heat out of your house and dumps it outside. The difference is a reversing valve that flips the refrigerant flow so the same equipment can heat in winter. When a Concord heat pump runs but won't cool, the cause is almost always a single component in that cooling cycle, not a dead system. We diagnose it exactly like an AC no-cooling call, then check the one part a heat pump adds.

Concord earns the diagnosis more than the coastal cities do. Summers here sit in the 90s from June through September with 100-plus stretches in heat waves, so a heat pump that loses even part of its capacity gets exposed fast. A unit that limped through a mild week in May falls apart on the first real Diablo Valley heat wave because there is no margin left.

Most of what we find is a worn part, low refrigerant from a slow leak, or a coil that needs cleaning. All fixable. The honest exception is an aging R-22 system where the repair math stops working, and when that's the case we tell you and put replacement numbers next to repair numbers on the same estimate.

Common causes

Failed run capacitor. This is the single most common Concord summer no-cool, on heat pumps and ACs alike. The capacitor that gives the compressor and outdoor fan their starting kick degrades in the heat. Once it weakens, the fan stops spinning or the compressor won't start, and the unit hums along without ever cooling. We test it with a meter and carry replacements on the truck.

Reversing valve stuck in heat mode. This is the failure unique to heat pumps. The valve that switches the system between heating and cooling can stick, or its solenoid can fail, leaving the unit producing warm air on a cooling call. We confirm it by reading line temperatures and testing the solenoid coil, then replace the valve or coil depending on which failed.

Low refrigerant from a leak. A heat pump that's low on charge loses cooling capacity and can ice the indoor coil. Refrigerant doesn't get used up, so low charge means a leak. We find it with electronic detection or nitrogen pressure testing, repair the leak, then weigh in a proper charge rather than topping off blind.

Dirty outdoor coil. Concord's dry summers leave the outdoor coil caked with dust and pollen, and a heat pump can't reject heat through a clogged coil. The compressor keeps running while head pressure climbs and the air at the registers barely cools. We clean the coil and verify the readings settle back where they belong.

Frozen indoor coil from low airflow. A clogged filter or weak blower starves the indoor coil of air. It drops below freezing, and ice blocks airflow until almost nothing cool reaches the registers. We thaw the coil first, then trace the airflow restriction that caused it so it doesn't lock up again the next afternoon.

Burned contactor. The contactor is the relay that powers the outdoor unit, and its contacts pit and burn over years of cycling. When it fails the compressor won't engage. We inspect it for pitting, test the coil, and replace it. It's an inexpensive part that gets missed when someone only checks refrigerant.

How we diagnose it

• Confirm the thermostat is calling for cool and the reversing valve is actually switching, since a heat pump stuck in heat mode mimics a refrigerant problem.
• Read suction, liquid, and supply-air temperatures to see whether the cooling cycle is running at all or running weak.
• Test the capacitor and contactor with a meter before touching refrigerant, because those are the cheapest and most common Concord summer failures.
• Check refrigerant pressures against the unit's target and inspect for leaks if the charge reads low.
• Inspect the outdoor coil and indoor filter, and on R-22 systems lay out repair-versus-replace numbers before any work.

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

Heat Pump Not Cooling in Concord: common questions

Nearby and related

Heat Pump Not Cooling near Concord: Walnut Creek · Martinez .

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