Red Seal RV Service Technician key terms

A documented procedure for isolating all energy sources to a unit before service, applying personal locks and warning tags so equipment cannot be re-energized or started while a technician is working on it.

The distance from exposed energized conductors within which a person could receive a second-degree burn from an arc; used to select approach distances and required protective equipment for 120/240 VAC RV service work.

Wearable gear such as safety glasses, gloves, arc-rated clothing, and hearing protection selected after a hazard assessment to reduce injury exposure during RV repair tasks.

Intentional connection of metal parts and the electrical system to earth so fault current has a low-impedance path back to the source, letting overcurrent devices open and limiting shock hazard.

A protective device that compares current on the hot and neutral conductors and trips when the difference indicates leakage, typically at 4 to 6 milliamps, protecting people from shock in wet locations.

The single intentional connection between the grounded conductor and equipment grounding conductor, made at the source only; an RV must not have this bond because it is made at the shore power pedestal.

A device that selects between shore power and an on-board generator so the two sources are never connected together, typically with a time delay to let the generator stabilize.

A converter changes 120 VAC shore power into 12 VDC to charge batteries and run low-voltage loads; an inverter reverses the process, producing 120 VAC from a 12 VDC battery bank.

The remaining capacity in a battery expressed as a percentage, estimated from resting voltage or a shunt-based monitor; it guides charging decisions and protects deep-cycle batteries from over-discharge damage.

Continuous low current drawn from the battery by devices such as clocks, detectors, and control boards when everything appears off; measured with a clamp meter to diagnose dead batteries.

A live measurement of the difference in voltage across a conductor or connection while current flows; excessive drop reveals resistance from corrosion or loose terminals that a static voltage check misses.

An instrument that measures LP gas pressure in inches of water column; used to verify regulated pressure at appliances and to perform timed leak-down tests on the piping system.

The pressure unit used for LP gas, equal to the height of a water column it supports; RV appliance manifold pressure is typically 11 inches WC for LP and 10 inches WC for natural gas.

A regulator assembly that reduces tank pressure to about 10 psi in a first stage and then to appliance manifold pressure in a second stage, giving steadier delivery as tank pressure and load change.

A timed pressure test in which the LP system is pressurized and isolated, then observed on a manometer; a pressure drop beyond the allowed limit indicates a leak requiring repair before service.

Sensors that generate a small voltage from heat to prove a pilot flame is lit; the thermocouple holds a single pilot-operated valve open, while a thermopile powers the main valve in millivolt systems.

The principle by which a direct spark ignition control senses a flame: the flame conducts current in one direction between the igniter/sensor and burner, producing a microamp signal the board reads as proof of ignition.

The air supplied to a burner for complete combustion; blocked or inadequate supply causes sooting, carbon monoxide production, and flame rollout, so appliance venting and openings must stay clear.

Recognition that CO is colorless and odorless, and that cracked heat exchangers, blocked flues, or reversed draft can cause poisoning; testing with a CO analyzer and verifying draft are required after repairs.

A water seal in the drain line that blocks holding tank odors from entering the coach; an air admittance valve lets air in behind draining water without allowing sewer gas out.

A built-in spray nozzle or external fitting that rinses the inside of the black tank after dumping, helping remove solids and sensor fouling; it must be connected through a vacuum breaker to prevent backflow.

A sliding gate valve on the gray or black tank outlet that opens to dump contents; a leaking seal or debris in the track causes slow seepage and must be serviced before the valve is left closed.

A demand pump pressurizes the potable system and shuts off at a set pressure; an accumulator tank absorbs pressure pulses, reducing pump cycling and stabilizing flow at fixtures.

Preparing the water system for freezing weather by draining lines, water heater, and tanks, then filling with potable antifreeze or blowing with air so trapped water cannot expand and split pipes or fittings.

A valve arrangement that isolates the water heater from the plumbing so it can be drained or bypassed during winterization, saving antifreeze and preventing damage from a dry-fired tank.

Superheat is refrigerant temperature above saturation at the evaporator outlet; subcooling is temperature below saturation at the condenser outlet. Together they show charge and metering-device performance.

Removing refrigerant from a sealed system into a recovery cylinder before opening it, as required by regulation; venting to atmosphere is prohibited and recovered refrigerant is weighed and recorded.

Roof coverings differ: EPDM and TPO are single-ply rubber or thermoplastic membranes, while fiberglass-reinforced panels are rigid; each accepts only compatible sealants and cleaners to avoid damage.

A bead of sealant applied over fasteners, seams, and roof penetrations to shed water; it must match the membrane type and be inspected and refreshed as it cracks or lifts.

A pourable sealant that flows out to form a smooth cap over horizontal roof seams and around vents; used on EPDM and TPO roofs where a flat, water-shedding surface is needed.

Separation of the exterior sidewall or roof skin from the substrate, often caused by water intrusion; detected by tapping for a hollow sound and by bulging, and it weakens structure and invites rot.

A hitch system using spring bars to transfer tongue weight to the trailer and front axle of the tow vehicle, leveling the combination and restoring steering and braking stability.

Tongue weight is the downward load at the coupler, generally 10 to 15 percent of trailer weight; payload is the cargo and passenger capacity remaining after the tow vehicle's own weight.

The maximum allowable total weight of a vehicle or trailer including cargo, fluids, and passengers as set by the manufacturer; exceeding it overloads tires, axles, and brakes.

A device or electronic system that resists trailer yaw caused by crosswinds, passing vehicles, or improper loading, helping keep the combination straight and preventing loss of control.

The bulb and wiper seals around a slide room opening that keep water and debris out; worn or torn seals allow intrusion and must be replaced and lubricated with compatible products.

Keeping both sides of a slide room moving together; on electric and hydraulic systems, out-of-sync travel causes binding and damage, corrected by a manufacturer-specific re-timing procedure.

A pump-and-cylinder system that extends jacks to level the coach; it requires checking fluid level with jacks retracted, bleeding air, and confirming the park brake interlock before operation.

Reproducing and documenting the customer's reported symptom before repair, then confirming the fix under the same conditions; this prevents unnecessary parts replacement and supports a defensible repair order.