Climate Control Systems

What you'll learn

• Explain what a vehicle climate control system must do, including defrosting and defogging as safety functions, and relate comfort to air temperature, humidity, air movement, radiant heat and the cabin heat load
• Explain sensible and latent heat and how pressure sets a refrigerant's boiling point, trace the refrigeration cycle, and convert gauge pressures to saturation temperatures with a correction for altitude
• Compare R-134a, R-1234yf and R-744 in pressure, global warming potential, flammability, fittings and oil, and identify refrigerant and deal with contaminated refrigerant correctly
• Apply federal and provincial refrigerant handling rules: certification, no venting, approved equipment, recovery cylinders and records
• Explain how fixed and variable displacement compressors and compressor clutches work and are protected and controlled, and diagnose clutch and compressor control faults with scan data, coil resistance and air gap
• Explain the condenser, evaporator, orifice tube, expansion valve, receiver-drier and accumulator, and use subcooling and superheat to separate airflow, charge and restriction problems
• Explain the engine cooling and heater systems, and diagnose weak heat by measuring engine temperature, heater hose temperatures and heater output, including air pockets and restricted heater cores
• Explain air distribution, blower speed control and door actuators, read commanded and actual door positions, and replace and calibrate actuators without repeat failures
• Explain the sensors, logic and network inputs of automatic climate control, and diagnose poor control by comparing sensor readings with real temperatures
• Explain electric compressors, PTC heaters and heat pumps in hybrids and electric vehicles, their coefficient of performance and battery thermal management, and work within high-voltage safety limits
• Find refrigerant leaks and perform a complete A/C service: identification, recovery, oil replacement, evacuation, decay test, charging by weight, leak check and performance test
• Diagnose a no-cool and a heater complaint from interview to verified repair, and document each as complaint, cause and correction with the readings that prove it