AC Not Cooling in Castro Valley

AC Not Cooling in Castro Valley

Castro Valley sits in a transitional climate, cooler than the inland valleys but with real summer afternoons. That is enough load to expose a weak system. A lot of the housing here is mid-century ranch construction, and much of the equipment is on its first or second replacement system, often well past the 15-year mark. When one of these will not cool, it is almost always a single worn part, not a dead system.

The two failures we see most are the cheap ones: a failed run capacitor and a pitted contactor. Both leave the AC humming or short-cycling without delivering cold air, and both are same-visit fixes. After that comes low refrigerant from a slow leak, a dirty condenser coil, or a frozen indoor coil from poor airflow. On older homes here, that poor airflow often traces back to leaky, under-insulated ductwork, which we can test and factor into the picture.

We measure the system's real pressures and temperatures before quoting. On older equipment, we are also straight about repair versus replace, especially on anything still running R-22 refrigerant, where a leak repair rarely pays off.

Common causes

Failed run capacitor. The number one Castro Valley cooling call. The compressor or fan hums but will not start, or starts and stalls. We test microfarads against the rating and replace it, typically $150 to $250 installed, same visit. On older equipment this is the first thing we check.

Pitted or failed contactor. The contactor is the relay that powers the outdoor unit, and on systems past 8 years the contacts pit and stop making clean connection. The condenser will not energize and the house stays warm. We inspect and replace it, a quick and inexpensive fix that prevents bigger compressor damage.

Low refrigerant from a leak. Aging ranch-home systems develop slow leaks. The unit runs long and the air is only slightly cool. We measure superheat and subcooling and find the leak. On R-22 systems we run the replacement math, because reclaimed R-22 is expensive and the system will leak again.

Dirty condenser coil. Years of dust and yard debris cake the outdoor coil so it cannot shed heat, and cooling drops off in the afternoon. We wash the coil and recheck head pressure. A clean coil also takes load off the capacitor and compressor, extending their life.

Frozen evaporator coil from weak airflow. Castro Valley's older homes often have leaky, under-insulated ducts and clogged filters that starve the indoor coil of airflow until it ices over and blows warm. We thaw it, fix the airflow restriction, and on install estimates we test the ducts since a retrofit sometimes pays back faster than equipment upgrades.

How we diagnose it

• Test the capacitor and contactor first, since those are the most common failures on Castro Valley's older equipment.
• Read refrigerant pressures and temperatures with gauges to measure actual performance instead of guessing.
• Check the refrigerant type, because R-22 systems change the repair-versus-replace math significantly.
• Inspect and clean the condenser coil and check the indoor coil and filter for airflow problems.
• On replacement estimates, test the ductwork for leakage that may be undercutting the whole system.

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

AC Not Cooling in Castro Valley: common questions

Nearby and related

AC Not Cooling near Castro Valley: San Leandro · Hayward · Dublin .

This is usually a ac repair in Castro Valley job. See our ac repair overview or the Castro Valley service area.