AC Not Turning On in San Ramon

AC Not Turning On in San Ramon

San Ramon is our home city. The shop is at 365 Reflections Circle on the Bishop Ranch side, and we respond fastest here because we're already here. That matters most in July and August, when Tri-Valley afternoons push past 95 and a dead AC turns a house uncomfortable in a hurry. Cooling is the heavy workload in San Ramon, so these systems run hard and the weak parts surface under load.

Here at home most of our no-start calls trace to a single part on a system that's been baking through Tri-Valley summers. A failed capacitor leads the list, with contactors, tripped breakers, and control-board fuses behind it. The 1980s and 90s tract homes that make up much of Westside, Twin Creeks, and Crow Canyon are at the age where their original condensers throw these faults regularly, and almost none of them need a full replacement.

There's a San Ramon pattern worth flagging. A lot of the older sections run original electrical panels that are near capacity, and on those homes a marginal compressor's startup surge trips the breaker more easily. We don't just reset it. We measure the inrush and figure out whether it's the AC, the breaker, or a panel that's maxed out, and we put what we find on the written estimate.

Common causes

Failed run capacitor. The most common no-start, and San Ramon's hot summers age capacitors faster than spec. A weak one leaves the compressor humming or silent. We meter it against the rated microfarads and replace it the same visit from the van.

Tripped breaker on an aging panel. Older Crow Canyon and downtown San Ramon homes run near panel capacity, so a compressor pulling a heavy startup surge trips the breaker. We measure the inrush rather than just resetting it, and tell you whether the fix is the AC, the breaker, or the panel itself.

Worn contactor. On the 1980s and 90s tract systems that cycle all summer, the contactor's contacts pit and weld until the outdoor unit gets no power. We inspect for burning and chatter and swap it when the contacts are spent.

Locked or overheated compressor. After repeated days over 95, a compressor can overheat and trip its internal overload, or on an end-of-life system actually seize. We check amp draw and whether it restarts once cool, and we're honest about which it is, because a locked compressor on a 25-year-old unit shifts the conversation toward replacement.

Dead thermostat batteries or miswire. A thermostat with dead batteries or a loose wire never sends the cooling call, and nothing downstream runs. We meter the thermostat terminals to confirm the signal is actually going out before we open the equipment.

Blown low-voltage fuse on the board. A short in the 24-volt control wiring blows the small board fuse and kills the system. We replace the fuse and trace the short, since a fuse that blows again means there's a wiring fault still in there.

How we diagnose it

• Confirm the thermostat is calling for cooling and rule out dead batteries.
• Check the breaker and outdoor disconnect, and on older homes measure compressor inrush against panel capacity.
• Test the capacitor's microfarad value, since San Ramon heat is the top capacitor killer.
• Inspect the contactor for pitting and confirm the compressor isn't locked or tripped on overload.
• Check the low-voltage control fuse and trace any short before repowering.

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

AC Not Turning On in San Ramon: common questions

Nearby and related

AC Not Turning On near San Ramon: Danville · Alamo · Dublin · Pleasanton .

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