# 120-Volt Electrical Systems Repair in Chino > OCRV Center diagnoses and repairs the 120-volt AC side of your coach in our Yorba Linda shop, from shore power and transfer switch faults to tripping breakers and dead outlets. Diagnostics start at $285 and are credited toward an authorized repair. The 120-volt AC system is the high-power side of the coach. It feeds the air conditioner, microwave, outlets, and the converter from shore power or the generator, routed through a transfer switch and a breaker panel. Because it carries household voltage, a loose connection or a failing transfer switch is both a nuisance and a real safety concern. All 120-volt work is done in shop at our Yorba Linda facility. ## 120-volt AC work we handle AC faults in an RV usually live in three places: where power comes in, how it gets distributed, and where it is protected. We test the shore inlet and cord for heat damage, verify the automatic transfer switch is actually switching cleanly between shore and generator, and check the breaker panel for loose lugs and back-fed neutrals. A GFCI outlet that will not reset or a breaker that trips under load points us straight to the failing leg. - Shore power inlet, cord, and pedestal connection faults - Automatic transfer switch testing and replacement - Breaker panel, GFCI, and outlet circuit repair - Reverse polarity and open ground correction - Air conditioner and microwave AC circuit diagnosis ## Safety-first AC diagnosis in shop A 120-volt fault is not the place to swap parts and hope. We power the coach from a controlled shore source, verify correct polarity and a solid ground first, then load test the circuits to find where voltage drops or heat builds. A scorched transfer switch contact or a melted inlet prong is a fire risk, so we look for the cause, not just the symptom. The diagnostic fee is credited back against an authorized repair, and a written estimate follows the diagnosis so you know the scope before any panel or transfer switch work begins. ## Frequently asked questions ### My RV breaker trips when I run the air conditioner, what causes that? It is usually one of a few things: an overloaded circuit, a weak or undersized shore connection, a failing transfer switch, or the air conditioner itself drawing too much as it ages. We load test the AC circuit to find which one it is, then repair the actual cause. ### What is a transfer switch and why does it matter? The automatic transfer switch selects between shore power and your generator and is supposed to switch cleanly between them. When its contacts burn or stick, you get no power on one source, flickering, or in a bad case overheating. We test it under load and replace it if the contacts are damaged. ### Can you fix outlets that only work on shore power but not the generator? Yes. That pattern points at the transfer switch or a specific leg of the AC distribution. We trace which source feeds which circuit and find where the path breaks, then repair it in shop. We do not offer mobile or roadside service. --- Source: https://oc-rv.com/services/120-volt-electrical-repair/ OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887. Phone (949) 799-3387. In shop only; insurance billed direct.