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(A7) Heating and Air Conditioning

Animations by ASE Content Area. Includes Tasks and Priority levels.

A: General: A/C System Diagnosis and Repair (click to expand)
A/C Does not Blow Cold (Task 3) (Priority 1)

A/C Performance Test (Task 3) (Priority 1)

A/C Proper Charge Level (Task 3) (Priority 1)

A/C System Operation (Task 3) (Priority 1)

Conduction (Task 2) (Priority 1)

Convection (Task 2) (Priority 1)

Does Compressor Engage (Task 3) (Priority 2)

Heat Transfer & Boiling (Task 2) (Priority 1)

Heat Transfer (Task 2) (Priority 1)

Heat Transfer Through Latent Heat (Task 2) (Priority 1)

HVAC System (Task 2) (Priority 1)

Identify Refrigerant, Economy (Task 4) (Priority 1)

Identify Refrigerant, Professional (Task 4) (Priority 1)

Leak Detector Maintenance (Task 6) (Priority 1)

Pressure Checks, Excess Pressure (Task 5) (Priority 1)

Pressure Checks, Low Pressure (Task 5) (Priority 1)

Radiant Heat (Task 2) (Priority 1)

Refrigerant Leak Detector (Task 6) (Priority 1)

Refrigerant Leak Detector Operation (Task 6) (Priority 1)

Refrigeration Cycle (Task 2) (Priority 1)


Task 1: Identify and interpret heating and air conditioning problems; determine needed action.

Task 2: Research vehicle service information including refrigerant/oil type, vehicle service history, service precautions, and technical service bulletins.

Task 3: Performance test A/C system; identify problems.

Task 4: Identify abnormal operating noises in the A/C system; determine needed action.

Task 5: Identify refrigerant type; select and connect proper gauge set/test equipment; record temperature and pressure readings.

Task 6: Leak test A/C system; determine needed action.

Task 7: Inspect condition of refrigerant oil removed from A/C system; determine needed action.

Task 8: Determine recommended oil and oil capacity for system application.

Task 9: Using a scan tool, observe and record related HVAC data and trouble codes.

B: Refrigeration System Component Diagnosis and Repair (click to expand)

A/C Does not Engage (Task 2) (Priority 2)

Accumulator Remove and Replace (Task 8) (Priority 2)

Block-Type, H Valve (Task 9) (Priority 1)

Clutch Application (Task 2) (Priority 2)

Compact Variable Compressor 1 (Task 3) (Priority 2)

Compressor Clutch Control (Task 2) (Priority 2)

Compressor Remove and Replace (Task 3) (Priority 2)

Condenser Remove and Replace (Task 13) (Priority 2)

Electric-Drive A/C Compressor (Task 4) (Priority 2)

Heat Pump System (Task 4) (Priority 2)

Heat Pump System 2 (Task 4) (Priority 2)

H-Valve (Task 9) (Priority 2)

Hybrid AC Compressor (Task 4) (Priority 2)

Inline Filter Install (Task 5) (Priority 3)

Inline Orifice Tube Install (Task 9) (Priority 1)

Internal Heat Exchanger (Task 6) (Priority 2)

Orifice Tube Remove and Replace (Task 9) (Priority 1)

Radio “Pop” Trick (Task 2) (Priority 2)

Remove and Replace Clutch Plate, Set Air Gap (Task 2) (Priority 2)

Remove and Replace Drive Belt (Task 13) (Priority 1)

Remove and Replace Service Valve (Task 6) (Priority 2)

Remove and Replace Service Valve Core (Task 6) (Priority 2)

Remove Orifice with Special Tool (Task 9) (Priority 1)

Scotch Yoke Compressor (Task 3) (Priority 2)

Scroll Compressor (Task 3) (Priority 2)

Service Fitting and Manual Coupler (Task 6) (Priority 2)

Service Fitting and Quick-Connect Coupler (Task 6) (Priority 2)

Swash Plate Compressor (Task 3) (Priority 2)

Test Compressor Clutch Circuit with Clamp Meter (Task 2) (Priority 2)

Test Compressor Clutch Circuit with Test Light (Task 2) (Priority 2)

Test Compressor Clutch Circuit with Volt Meter (Task 2) (Priority 2)

TXV Operation (Task 9) (Priority 1)

Vane Compressor (Task 3) (Priority 2)

Wobble Plate Compressor (Task 3) (Priority 2)


Task 1: Inspect, remove, and/or replace A/C compressor drive belts, pulleys, tensioners and visually inspect A/C components for signs of leaks; determine needed action.

Task 2: Inspect, test, service and/or replace A/C compressor clutch components and/or assembly; check compressor clutch air gap; adjust as needed.

Task 3: Remove, inspect, reinstall, and/or replace A/C compressor and mountings; determine recommended oil type and quantity.

Task 4: Identify hybrid vehicle A/C system electrical circuits and service/safety precautions.

Task 5: Determine need for an additional A/C system filter; perform needed action.

Task 6: Remove and inspect A/C system mufflers, hoses, lines, fittings, O-rings, seals, and service valves; perform needed action.

Task 7: Inspect for proper A/C condenser airflow; determine needed action.

Task 8: Remove, inspect, and replace receiver/drier or accumulator/drier; determine recommended oil type and quantity.

Task 9: Remove, inspect, and install expansion valve or orifice (expansion) tube.

Task 10: Inspect evaporator housing water drain; perform needed action.

Task 11: Diagnose A/C system conditions that cause the protection devices (pressure, thermal, and/or control module) to interrupt system operation; determine needed action.

Task 12: Determine procedure to remove and reinstall evaporator; determine required oil type and quantity.

Task 13: Remove, inspect, reinstall, and/or replace condenser; determine required oil type and quantity.

C: Heating, Ventilation, and Engine Cooling Systems Diagnosis and Repair (click to expand)

Heater Core Remove and Replace (Task 4) (Priority 2)

Heater Operation (Task 3) (Priority 2)


Task 1: Inspect engine cooling and heater systems hoses and pipes; perform needed action.

Task 2: Inspect and test heater control valve(s); perform needed action.

Task 3: Diagnose temperature control problems in the HVAC system; determine needed action.

Task 4: Determine procedure to remove, inspect, reinstall, and/or replace heater core.

D: Operating Systems and Related Controls Diagnosis and Repair (click to expand)

Automatic Temperature Control, ATC Air Quality (Task 8) (Priority 2)

Automatic Temperature Control, ATC Sun Load (Task 8) (Priority 2)

Automatic Temperature Control, ATC Temperature, Cool (Task 8) (Priority 2)

Automatic Temperature Control, ATC Temperature, Cool, Adjust (Task 8) (Priority 2)

Automatic Temperature Control, ATC Temperature, Heat (Task 8) (Priority 2)

Automatic Temperature Control, ATC Temperature, Humidity (Task 8) (Priority 2)

Blower (Task 1) (Priority 1)

Blower Control, Manual (Task 1) (Priority 1)

Blower Control, PWM (Task 1) (Priority 1)

Compressor Clutch RPM Sensor (Task 1) (Priority 1)

Compressor Temperature Sensor (Task 1) (Priority 1)

Fan Control (Task 1) (Priority 1)

Fan, Electronic Control (Task 1) (Priority 1)

HVAC Functions (Task 4) (Priority 2)

HVAC Modes, Air Inlet & Discharge (Task 6) (Priority 1)

HVAC Modes, Temperature Change Cool (Task 5) (Priority 3)

HVAC Modes, Temperature Change Heat (Task 5) (Priority 3)

Remove and Replace Cabin Air Filter (Task 6) (Priority 1)

Test Blower Motor with Clamp Meter (Task 1) (Priority 1)

Test Blower Motor with Test Light (Task 1) (Priority 1)


Task 1: Inspect and test HVAC system blower motors, resistors, switches, relays, wiring, and protection devices; determine needed action.

Task 2: Diagnose A/C compressor clutch control systems; determine needed action.

Task 3: Diagnose malfunctions in the vacuum, mechanical, and electrical components and controls of the heating, ventilation, and A/C (HVAC) system; determine needed action.

Task 4: Inspect and test HVAC system control panel assembly; determine needed action.

Task 5: Inspect and test HVAC system control cables, motors, and linkages; perform needed action.

Task 6: Inspect HVAC system ducts, doors, hoses, cabin filters, and outlets; perform needed action.

Task 7: Identify the source of HVAC system odors.

Task 8: Check operation of automatic or semi-automatic HVAC control systems; determine needed action.