ASE H7 HVAC (Transit Bus) study plan

ASE H7 HVAC (Transit Bus) · Give each week a clear focus.

8 weeks · About 7 hours per week

Week 1

HVAC System Fundamentals, Safety, and Regulations & System Diagnosis and Performance Testing

Diagram the transit bus HVAC refrigerant circuit from memory, labeling compressor, condenser, receiver-drier, expansion valve, evaporator, and accumulators
Explain the pressure-temperature relationship for the refrigerant used and convert gauge readings to saturation temperatures for at least 10 sample readings
Identify safety hazards specific to transit bus HVAC (high-voltage inverter cooling, refrigerant in enclosed passenger compartments, roof-mounted service access)
List the regulations and standards that govern refrigerant handling and passenger-compartment ventilation

A one-page hand-drawn system schematic plus a 10-row gauge-reading conversion worksheet checked against a PT chart

Week 2

Compare compressor types used on transit buses (reciprocating, scroll, screw) and describe how each compresses refrigerant
Trace the compressor drive path from engine or electric motor through clutch, belts, and couplings
Explain clutch engagement circuits and the role of the pressure and temperature switches that enable them
Describe compressor lubrication and oil circulation requirements and what happens when oil return is poor

A written comparison table of three compressor types with drive-path sketches and a 15-question self-quiz scored at 80% or higher

Week 3

Perform a recovery/recycling procedure on a training or scrap system following EPA Section 608 rules, including evacuation and leak-check steps
Demonstrate proper cylinder handling, filling limits, and identification of recycled versus virgin refrigerant
Explain the difference between recovery, recycling, and reclamation and when each is permitted
Document a refrigerant handling log that would satisfy an auditor

A completed refrigerant handling log and a signed skills checklist covering recovery, evacuation, and cylinder safety

Week 4

Trace the control wiring from the driver's HVAC panel through relays, fuses, and the electronic control module to the actuators
Test a thermistor or pressure transducer with a multimeter and interpret the voltage-to-temperature or voltage-to-pressure relationship
Explain how an expansion valve and an orifice tube each meter refrigerant and how each responds to load changes
Diagnose a stuck-closed versus stuck-open expansion valve from pressure and temperature symptoms

A control-circuit trace diagram with measured sensor values and a written diagnosis of two simulated expansion-valve faults

Week 5

Describe airflow through condenser and evaporator and identify how fouling, fan failure, and restricted airflow change pressures
Explain how blowers, dampers, and ductwork deliver conditioned air to the passenger compartment
Trace refrigerant lines and identify where restrictions, kinks, and moisture can cause performance loss
Explain how a restricted condenser versus a restricted evaporator produces different gauge patterns

A labeled airflow and refrigerant-line diagram with a one-paragraph fault explanation for each of three restriction scenarios

Week 6

Trace the coolant or electric heating circuit from heat source through the heater core and controls
Explain defrost operation, including damper position, blower speed, and how defrost performance is verified
Describe how the HVAC system manages humidity and windshield fogging on a loaded transit bus
Identify failure modes of heater control valves, blend doors, and defrost actuators

A heating and defrost circuit diagram with a written troubleshooting sequence for a no-heat and a no-defrost complaint

Week 7

Perform a full performance test: record ambient conditions, vent temperatures, high and low side pressures, and compressor cycling
Interpret superheat and subcooling readings to judge charge level and component health
Use scan-tool or built-in diagnostics to read fault codes and correlate them with measured values
Build a symptom-to-cause matrix covering at least eight common complaints

A completed performance test worksheet with superheat and subcooling calculations and an eight-row symptom-to-cause matrix

Week 8

Take a timed 60-question practice exam across all nine domains and review every missed item
Re-drill the two weakest domains identified by the practice exam until each is above 80%
Re-state the safety and refrigerant-handling rules that appear most often on the exam
Walk through three full diagnostic scenarios end to end, from complaint to verified repair

A scored 60-question practice exam with a written review log of every missed question and a final weak-area action list

Week 2: Score 80% or higher on the compressor and fundamentals self-quiz and correctly draw the refrigerant circuit from memory

Week 4: Correctly diagnose both simulated expansion-valve faults and explain the control-circuit trace without notes

Week 6: Explain heating and defrost operation and produce a working troubleshooting sequence for no-heat and no-defrost complaints

Week 8: Score 80% or higher on the timed 60-question practice exam with all missed items reviewed and logged