Exam Cheat Sheet · Quick Reference
Oklahoma HVACR Journeyman Unlimited
Oklahoma · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
70
Passing score
70%
Exam time
180 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Oklahoma State Portion 70 questions
Electrical Knowledge and Controls
15 Q · 21%
Reading and interpreting pictorial and ladder wiring diagramsOhm's law, Watt's law, and basic circuit calculationsSeries, parallel, and series-parallel circuit fundamentalsSingle-phase and three-phase AC motor types and starting methodsMotor starting relays: current, potential, solid-state, and PTC typesMotor protection devices: fuses, circuit breakers, and bimetal devicesTemperature and pressure motor controls: range and differential adjustmentElectrical test equipment: voltmeters, ohmmeters, ammeters, and multimetersControl transformers and 24-volt control circuits
Natural Gas
10 Q · 14%
Gas piping materials, fittings, and approved pipe types (steel, copper, CSST, polyethylene)Gas piping sizing methods (longest length, branch length, hybrid pressure) and capacity tablesGas piping pressure requirements, testing, and leak checkingCombustion air requirements for gas appliances (indoor, outdoor, and combined methods)Venting systems for gas appliances (Type B, single-wall, chimney, direct-vent) and vent sizingGas furnace components and operation (burners, gas valves, ignition systems, safety controls)Combustion fundamentals (air-fuel ratio, complete/incomplete combustion, flue gas analysis)Appliance installation requirements, clearances, and prohibited locations
Air Distribution Systems
16 Q · 23%
Duct system types and configurations (radial, extended plenum, reducing trunk, perimeter loop, SDHV)Duct construction materials and joining methods (metallic, fiberglass, flexible, ductboard)Duct sizing principles and procedures (aspect ratio, friction rate, ACCA Manual D)Registers, diffusers, grilles, and dampers (types, placement, airflow control)Duct sealing, insulation, and leakage testing (mastic, metal tape, blower door, duct blaster)Ventilation requirements and air changes per hour calculationsFans and air movement measurement (anemometers, pitot tubes, flow hoods, manometers)Indoor air quality and exhaust system requirements per IMC Chapter 5 and Chapter 6
Refrigeration and Air Conditioning Systems
16 Q · 23%
Compression refrigeration cycle components and operationCompressor types and configurations (reciprocating, rotary, scroll, screw, centrifugal)Metering devices (capillary tube, TXV, AXV, EEV, fixed orifice)Evaporator and condenser types, construction, and defrost methodsRefrigerant classification, properties, and environmental regulations (ODP, GWP, Clean Air Act)Refrigerant handling procedures (recovery, evacuation, charging, superheat and subcooling checks)Refrigerant flow components (filter-driers, receivers, check valves, solenoid valves, pressure-regulating valves)Heat pump operation, reversing valves, and system configurations
Heating Systems
10 Q · 14%
Gas-fired heating systems: combustion, gas valves, burners, and ignition systemsOil-fired heating systems: fuel oil properties, oil burners, combustion efficiency testing, and fuel delivery systemsHydronic heating system components: boilers, circulating pumps, expansion tanks, and terminal unitsElectric heating systems: resistance elements, electric furnaces, duct heaters, and baseboard unitsForced-air furnace types and heat exchanger operationHeating and cooling load calculations: heat loss, R-values, U-values, and design temperaturesVenting and chimney requirements for heating appliances per IFGC and IMCHeating system controls: thermostats, aquastats, safety controls, and zone controls
Safety
3 Q · 4%
Lockout/tagout (LOTO) procedures for electrical safetyFire hazard identification and fire extinguisher use (P.A.S.S. method and fire classes)Refrigerant cylinder handling, storage, and pressure hazardsPersonal protective equipment (PPE) selection and useSafety Data Sheets (SDS) and Globally Harmonized System (GHS) chemical labelingBreathing hazards and respiratory protection (air-purifying vs. supplied-air respirators)Ladder, scaffolding, and fall protection safe work practicesOSHA regulations, hazard assessment, and safety certifications
Key Distinctions
Pictorial Wiring DiagramvsLadder Diagram
Pictorial diagrams show approximate physical device locations and wire colors, while ladder diagrams show order of component operation using horizontal rungs between two vertical power lines.
Chapter 16, Section 16.1.1Motor StartervsContactor
A motor starter includes built-in overload protection, whereas a contactor does not.
Modern Refrigeration and Air Conditioning, Chapter 16, Section 16.3.5 — Contactors and Motor StartersBuilding-Related Illness (BRI)vsSick Building Syndrome (SBS)
BRI is a specifically diagnosable illness whose symptoms do not disappear when the occupant leaves the building, while SBS has no identifiable illness or specific cause and symptoms disappear upon leaving.
Modern Refrigeration and Air Conditioning, Page 730Hard LockoutvsSoft Lockout
A hard lockout shuts the furnace down for an unspecified time requiring a power interruption to reset, while a soft lockout automatically retries ignition after a waiting period.
Modern Refrigeration and Air Conditioning, Page 1129PTC Thermistor (cool)vsPTC Thermistor (heated to set point)
When cool the PTC thermistor has low resistance (3–12 Ω) and carries current instead of the run capacitor; once heated to its set point its resistance rises dramatically (10–20 kΩ), forcing current through the run capacitor instead.
Chapter 16, Section 16.3.5 — Positive Temperature Coefficient RelaysCurrent Relay (weight-operated)vsCurrent Relay (rotary solenoid)
A weight-operated current relay must be mounted level, while a rotary solenoid current relay can be mounted in any position.
Modern Refrigeration and Air Conditioning, Chapter 16, Section 16.3.5 — Current RelaysK-value (Thermal Conductivity)vsC-value (Thermal Conductance)
K-value measures heat transfer through a standardized one-inch thickness of material, while C-value is based on the material's actual measured thickness.
Modern Refrigeration and Air Conditioning, Page 986Supplied-Air RespiratorvsAir-Purifying Respirator
A supplied-air respirator provides supplemental oxygen and must be used when oxygen levels are below 19.5%, whereas an air-purifying respirator only filters existing air and cannot be used in oxygen-deficient environments.
HVACR Textbook, Chapter 2, Section 2.3.4 Respiratory ProtectionSeries CircuitvsParallel Circuit
In a series circuit there is only one current path so opening any device breaks the entire circuit, while in a parallel circuit each load has its own path so other loads continue operating if one opens.
Chapter 12, Section 12.4.2Range Adjustment (Low-Pressure Control)vsDifferential Adjustment (Low-Pressure Control)
Turning the range adjustment screw clockwise raises both cut-in and cut-out pressures equally, while turning the differential adjustment screw clockwise raises only the cut-out pressure.
Chapter 16, Section 16.3.4 — Low-Pressure Motor ControlsHot-Surface Ignition (HSI) Glow CoilvsFlame Rod
The glow coil is used only for ignition and cannot sense the flame, while the flame rod performs flame sensing via flame rectification to confirm burner operation.
Modern Refrigeration and Air Conditioning, Pages 1126-1128 (Sections 41.5.4 and 41.6.1)Radial Duct SystemvsPerimeter Loop Duct System
A radial system runs individual branch ducts directly from a central plenum to each room with no trunk duct, while a perimeter loop system uses ductwork embedded in a concrete slab with branch ducts connecting to a continuous perimeter duct.
Modern Refrigeration and Air Conditioning, Page 755Key Terms
Duct Sizing Method (Single Dwelling Unit) International Mechanical Code 2021, Section 603.2
Per IMC 2021 Section 603.2, ducts in a single dwelling unit shall be sized per ACCA Manual D, the appliance manufacturer's instructions, or other approved methods.
Duct Leakage Test Pressurization Modern Refrigeration and Air Conditioning, Page 792
Per Modern Refrigeration and Air Conditioning (Page 792), ductwork is pressurized to +25 Pa with respect to the conditioned space during a duct leakage test.
Maximum Duct Leakage (Pre-Air-Handler Installation) Modern Refrigeration and Air Conditioning, Page 793
Per Modern Refrigeration and Air Conditioning/IECC (Page 793), maximum allowable duct leakage when tested before the air handler is installed is 3 cfm per 100 ft² of conditioned space.
High-Pressure Motor Control Cut-Out Setting Chapter 16, Section 16.3.4 — High-Pressure Motor Controls
Per Chapter 16 Section 16.3.4, a high-pressure motor control safety device is typically set to cut out at 20% above normal head pressure.
Low-Voltage Control Circuit Chapter 17, Section 17.1.1
Per Chapter 17 Section 17.1.1, low-voltage control circuits in HVACR systems typically operate at 24 V, stepped down by a control transformer from line voltage.
Blower Door Test – cfm50 Modern Refrigeration and Air Conditioning, Page 791
Per Modern Refrigeration and Air Conditioning (Page 791), cfm50 is the measured airflow through a blower door fan when indoor pressure is held at −50 Pa with respect to outdoors.
Plenum Branch Duct Connection Rule Modern Refrigeration and Air Conditioning, Page 769
Per Modern Refrigeration and Air Conditioning (Page 769), branch ducts must always connect at the sides of a plenum, never the end, to prevent excessive airflow to that duct.
Velocity Pressure Modern Refrigeration and Air Conditioning, Page 710
The difference between total air pressure and static air pressure, measured by a pitot tube; total pressure equals static pressure plus velocity pressure.
Differential (Pressure/Temperature Control) Chapter 16, Section 16.2.2
The difference between a control's cut-out and cut-in values, representing the swing during which the system cycles on and off.
Solid-State Relay (SSR) Chapter 16, Section 16.3.5 — Solid-State Relays
A motor-starting relay that uses electronic components such as transistors, SCRs, or triacs to switch circuits with no physical movement of mechanical parts.
Current-Limiting Fuse Chapter 16, Section 16.4.1
A fuse using temperature-sensitive resistors that open when current exceeds the limit and the fuse heats up, then re-close after cooling, preventing motor current from exceeding locked-rotor amperage.
Multipurpose Fuse Chapter 16, Section 16.4.1
A fuse combining fast-acting and time-delay characteristics: it tolerates brief high starting currents but blows immediately if current exceeds 500% of its maximum rating.
Flame Rectification Modern Refrigeration and Air Conditioning, Pages 1126-1128 (Sections 41.5.4 and 41.6.1)
The process by which a flame rod sends a microamp DC signal back to the ignition control module to confirm burner flame presence in a hot-surface ignition system.
Draft (Oil/Gas Furnace) Modern Refrigeration and Air Conditioning, Page 1155
The movement of flue gas measured in inches of water column (in. WC) by a draft gauge, indicating the rate of flue gas flow through the heat exchanger.
Formulas to Know
Ohm's Law – Resistance
R (Ω) = E (V) ÷ I (A)Ohm's Law – Current
I (A) = E (V) ÷ R (Ω)Ohm's Law – Voltage
E (V) = I (A) × R (Ω)Watt's Law – Power (single-phase)
P (W) = I (A) × E (V)Series Circuit – Total Voltage Drop
V_T = VD₁ + VD₂ + VD₃ + … (sum of all individual voltage drops equals applied voltage)Control Differential
Differential = Cut-out value − Cut-in valueSubcooling
Subcooling (°F) = Condensing temperature at operating pressure − Actual liquid temperatureTotal Air Pressure
Total pressure = Static pressure + Velocity pressure