ASE S7 Air Conditioning Systems & Controls (School Bus) study plan
ASE S7 Air Conditioning Systems & Controls (School Bus) · Give each week a clear focus.
8 weeks · About 6 hours per week
A/C System Inspection, Diagnosis, and Repair
Map the full A/C system layout on a school bus and label every component, from compressor to evaporator, on a hand-drawn diagram
Explain the pressure-temperature relationship of refrigerant and how it drives cooling and heating in the system
Walk through a systematic performance test procedure (vent temperature, ambient temperature, gauge readings) and record expected values
List the top ten customer complaints on bus A/C systems and the first diagnostic step for each
Your checkpoint
A one-page system diagram with component labels plus a completed performance-test checklist with pass/fail criteria
A/C System Inspection, Diagnosis, and Repair & Safety, Environmental, and Regulatory Compliance
Diagnose common A/C faults (low charge, restriction, air in system, weak compressor) using gauge and temperature readings
Demonstrate safe handling of refrigerant cylinders, recovery equipment, and personal protective equipment
Identify regulatory requirements for refrigerant handling and recordkeeping that apply to school bus fleets
Document a step-by-step diagnostic decision tree for a no-cooling complaint
Your checkpoint
A written diagnostic decision tree covering at least six fault scenarios with the gauge/temperature evidence for each
Refrigerant Recovery, Recycling, and Handling & Safety, Environmental, and Regulatory Compliance
Perform a complete refrigerant recovery and recycling sequence on a trainer or mock setup, narrating each step
Explain the difference between recovery, recycling, and recharging, and when each applies
Calculate refrigerant charge by weight and verify against the vehicle specification
Describe proper evacuation procedure including required vacuum level and hold time
Your checkpoint
A recovery-to-recharge procedure sheet with vacuum targets, charge weights, and a self-scored practice run
Compressor and Drive Systems
Identify compressor types used on school buses and describe the internal function of each major part
Diagnose compressor drive problems including belt tension, pulley alignment, clutch operation, and mount integrity
Measure and interpret clutch coil resistance and clutch air-gap clearance against specification
Explain oil circulation, oil type selection, and the consequences of incorrect oil charge
Your checkpoint
A compressor inspection and drive-system checklist completed on a real or simulated unit, with measured values recorded
Condenser, Evaporator, and Refrigerant Lines & Expansion Devices and Refrigerant Flow Control
Trace refrigerant lines and identify each fitting, hose, and connection type used on a bus A/C system
Diagnose condenser and evaporator performance problems including airflow restriction, fin damage, and internal blockage
Compare expansion valve, orifice tube, and block valve operation and identify the symptoms of each failing
Explain how a restricted expansion device changes high-side and low-side pressures and vent temperature
Your checkpoint
A component-by-component inspection log for condenser, evaporator, lines, and expansion device with at least three induced or observed faults diagnosed
Electrical and Electronic Controls
Read and interpret an A/C control wiring schematic, tracing power, ground, and signal paths for the compressor clutch and blower
Test pressure switches, thermistors, relays, and control modules with a multimeter and describe expected readings
Diagnose an electrical no-cooling fault by isolating the open or shorted circuit
Explain how the body control module or HVAC controller manages compressor cycling and blower speed
Your checkpoint
A traced schematic with measured voltages and resistances at each test point, plus one electrical fault diagnosed to root cause
HVAC Air Distribution and Blower Systems & Heating and Defrost Systems
Diagnose blower motor and resistor or PWM control faults across all speed settings
Evaluate air distribution door operation, mode selection, and duct airflow on a bus body
Test heater core flow and temperature output and diagnose a no-heat or weak-heat complaint
Verify defrost performance and explain the safety requirement for adequate driver visibility
Your checkpoint
A completed airflow and heater/defrost performance test sheet with blower speeds, vent temperatures, and defrost clearing time recorded
A/C System Inspection, Diagnosis, and Repair & Refrigerant Recovery, Recycling, and Handling & Electrical and Electronic Controls & Safety, Environmental, and Regulatory Compliance
Complete a full timed practice exam across all nine domains and score it against the domain weightings
Re-teach the three weakest domains by writing a short explanation of each key concept from memory
Rehearse the end-to-end job: inspect, diagnose, recover, repair, evacuate, recharge, and verify performance
Confirm readiness on safety and environmental compliance items including PPE, refrigerant handling, and documentation
Your checkpoint
A scored practice exam with a written remediation list for any domain scoring below 80 percent
Milestones
Week 2: Can diagnose at least six A/C fault scenarios from gauge and temperature readings without notes
Week 4: Can perform a complete recovery-to-recharge sequence and correctly calculate charge weight
Week 6: Can trace a compressor clutch circuit on a schematic and locate an induced electrical fault
Week 8: Scores 80 percent or higher on a full weighted practice exam with no domain below 70 percent