RV Service in San Juan Capistrano

Two systems share one coach. The 12 volt direct current side runs from the house batteries and powers lights, water pump, fans, slide and jack motors, the furnace blower, and the control boards of most appliances. The 120 volt alternating current side comes from shore power, the generator or an inverter, and powers roof air, the microwave, outlets and the converter that recharges the batteries. Understanding which side a symptom sits on is most of the diagnosis.

The converter is where the two meet, and it is the most commonly misdiagnosed component on a coach. It takes 120 volt input and produces regulated 12 volt output to charge batteries and feed DC loads while you are plugged in. When it fails, everything appears to work for a day or two on stored battery capacity, then progressively dies. Owners replace batteries at that point, and the new batteries die too, because the fault was never in the batteries.

The transfer switch is the second suspect. It decides whether the coach draws from shore or generator, and it does so with contactors that arc, pit and eventually weld or fail open. A coach that works perfectly on shore power and has nothing on generator, or the reverse, is describing a transfer switch far more often than it is describing a generator problem.

Grounds are the third. Vibration and corrosion attack ground connections harder than anything else, and a marginal ground produces symptoms that make no logical sense: lights that dim when the pump runs, a fridge board that resets when the slide moves, a fault that comes and goes with temperature. Chasing those without a meter is how owners spend hundreds of dollars on parts that were never bad.

Owners increasingly want to run without hookups, and that means panels, controllers, batteries and an inverter working as a designed system rather than as four purchases. The most common failed upgrade is a large lithium bank installed behind a converter that was built to charge lead acid. Lithium chemistry needs a different charge profile, and a lead-acid converter will either undercharge the bank permanently or push it in a way its battery management system keeps interrupting.

Wire gauge is the second failure. A 3000 watt inverter at 12 volts draws over 250 amps under load. That current needs cable, lugs, and fusing sized for it, on runs kept as short as physically possible. Undersized cable does not simply underperform; it heats, and heat inside a laminated wall is a genuinely serious problem. Every high current run in a proper install gets fused at the source and routed with abrasion protection through any panel penetration.

Roof mounting is the third. Every panel foot and every cable gland is a hole in a membrane that is the only thing between the ceiling and the sky. Mounts get bedded in butyl and lap sealed, cable entries use a proper gland rather than a sealant blob, and panel placement accounts for shading from the AC shrouds and vent covers that are already up there.

OCRV Center sizes these installs from actual consumption rather than from a wish list. That means measuring what the coach draws over a realistic day, then specifying array, controller, bank and inverter to match, along with any converter or distribution changes the new chemistry requires.

Onboard generators fail predictably, and almost always from disuse rather than from hours. Fuel sits in a carburetor bowl over a Southern California summer, the light ends evaporate, and what is left varnishes the jets. The unit cranks, catches for two seconds and dies, or runs but drops out under load. Owners describe this as a dead generator; it is usually a fuel system that needs cleaning and a service the unit has not had in three years.

The genuine failures cluster in three places. Brushes and slip rings wear and lose contact, producing output that is present at no load and collapses when the roof air compressor starts. Control boards fail from heat and vibration, giving fault codes that need the manufacturer service literature to interpret. Mounting isolators collapse, which lets the whole assembly transmit vibration into the coach structure and progressively damage its own wiring and fuel line connections.

Load testing is what separates a real diagnosis from a guess. A generator that runs beautifully on the bench with nothing connected tells you very little. Under a resistive load bank, output voltage and frequency under a stepped load reveal whether the alternator end, the governor or the fuel delivery is the actual limit. That test takes time and it is why generator diagnosis is billable.

OCRV Center services Onan, Generac, Cummins and Kohler units among others, and treats the generator as a house system rather than a drivetrain component. Engine rebuild and transmission work on the chassis are outside scope, but generator service, repair and replacement are handled in the building.

Propane in a coach runs at a regulated 11 inches of water column, which is a very low pressure, and nearly every LP complaint traces back to that number being wrong. A regulator that has drifted high produces yellow lazy flames, sooting and appliances that lock out. A regulator that has drifted low produces burners that light and then starve, a water heater that cycles off mid-shower, and a furnace that fires and quits after ninety seconds.

Testing is done with a manometer, not by observation. The technician verifies static pressure, then working pressure with the highest-demand appliance running, then performs a timed pressure drop test on the whole system to detect leaks that a soap bubble check would miss. That last test is the one that matters most, because a slow leak inside a wall cavity gives no smell outside and no visible sign at all.

The appliances themselves each fail in a characteristic way. Water heaters fail at the thermocouple or the electronic ignition board, or accumulate enough sediment to insulate the burner side of the tank. Furnaces fail at the sail switch, which proves airflow before allowing gas, and at the limit switch, which shuts things down when a duct is blocked. Absorption refrigerators fail when the burner orifice clogs or when the cooling unit itself develops a blockage, which is a replacement rather than a repair.

Anything involving LP at OCRV Center gets a documented leak test before the coach is released, and a $45 hazmat charge applies where LP, refrigerant or chemicals are handled, covering compliant capture and disposal.

Coach plumbing is PEX, poly or occasionally copper, joined with crimp or push fittings, running through walls and under floors that flex constantly while the vehicle moves. Fittings work loose. Lines chafe where they pass through a framing member without a grommet. Freeze damage from a single overlooked winterization splits a fitting that then leaks only under pump pressure, which is why the puddle appears the day after you fill the tank rather than the day you find the crack.

Distinguishing supply leaks from drain leaks from external leaks is the first job on any water complaint. Supply leaks are pressure dependent: they appear when the pump runs or when city water is connected, and stop when the system is depressurized. Drain leaks appear only when a fixture is used. External leaks appear after rain regardless of what the plumbing is doing. Each points at a completely different repair, and the diagnosis is done by isolating pressure and observing.

Holding tanks fail at the seams, at the fitting bosses, and at the ABS flange where the toilet meets the black tank. Cracks in a tank that is still in place can occasionally be repaired with a plastic weld from the accessible side, but tanks are usually captured above a belly pan or between frame rails, which means dropping the pan and sometimes the tank itself. That access work is most of the labor on a tank job.

Sensors deserve their own note. Black tank level sensors read solids stuck to the probe rather than fluid level, and no amount of chemical fixes a sensor that is coated. Replacement with an external ultrasonic sender is often the more durable answer.

Roof air units are sealed systems and they are not field-recharged in most cases. A unit that runs but does not cool is usually short on airflow rather than short on refrigerant: a clogged return filter, a crushed or disconnected duct, or a failed condenser fan. A unit that trips a breaker after twenty minutes is describing a compressor drawing high current, often because the start capacitor has degraded and the compressor is struggling to come up to speed against high head pressure.

Ducted systems fail differently from non-ducted. On a ducted coach, air travels through a ceiling plenum with registers spaced along the length, and a single crushed duct at a slide opening starves everything downstream of it. Owners read that as a weak air conditioner. It is a distribution problem, and it is diagnosed by measuring supply temperature at each register rather than by feeling the air.

Furnaces are forced-air LP units with a proving sequence: the blower spins up, the sail switch confirms airflow, then the board allows gas and sparks ignition. Anything that reduces airflow, including a blocked return, a bad blower wheel or a collapsed duct, stops the sequence at the sail switch and produces a furnace that blows cold and then shuts off. That is the single most common winter complaint on a coach.

Hydronic systems, found on higher-end diesel coaches, heat a glycol loop and distribute it to fan coils and to domestic hot water. They fail at the burner, at the circulation pump, and at the loop itself where air becomes trapped. OCRV Center services all three types, including Aqua-Hot and Oasis style systems.

It starts with a conversation that is more useful than owners expect. When did it start, what changed just before, which power source were you on, what does it do when it is cold versus warm, and does it repeat or come and go. Intermittent faults are the expensive ones, and a good history turns a four hour hunt into a one hour confirmation.

Then the technician verifies the complaint on the vehicle. This step gets skipped in bad shops and it is where a surprising number of jobs end, because the reported symptom and the observed symptom are different things. A coach reported as having no hot water may have a working water heater and a failed mixing valve. A coach reported as having a dead battery may have a working battery and a disconnect switch that has lost contact.

Measurement follows verification. Voltage under load, not at rest. Current draw at the branch, not at the panel. Gas pressure with the appliance running, not static. Temperature split across an evaporator, not a hand held in front of a vent. Those measurements produce a diagnosis with a number attached, which is what makes a repair recommendation defensible rather than a guess dressed up in confidence.

The $150 systems estimate covers that initial evaluation and credits back against an authorized repair. Where the fault requires extended instrumented work, such as a parasitic draw hunt or a control module that only misbehaves at temperature, that time bills at $285 per hour with a one hour minimum and credits the same way. To book, call (949) 799-3387.