ASE A7 Heating Air Conditioning Exam

A CCOT system has a high high side. Technician A says to suspect the thermostatic expansion valve. Technician B says this system contains an orifice tube. Who is correct? - ANSWER-TECH B is correct. A clogged orifice tube will result in high high side pressure. It can become clogged with contaminants, debris from a damaged compressor, or a broken desiccant bag releasing desiccant into the refrigerant. A vehicle's air conditioning performance is reduced at low speeds and stop lights, but cools at highway speeds. Which of these is MOST likely the cause of this condition? A. A low refrigerant charge. B. A missing fan shroud. C. A normal condition. D. A faulty compressor clutch relay. - ANSWER-Answer B is correct. A properly fitting and fastened fan shroud is vital for good A/C and engine performance. Many of these shrouds and dams create a low pressure area behind the radiator and condenser. Loose or missing shrouds will be especially noticeable as the vehicle slows and ram air is reduced. Two technicians are discussing an inoperative electric blend door in an automatic air conditioning system. Technician A says to inspect the blend door's wiring and connections for an open circuit. Technician B says to troubleshoot this circuit with a test light. Who is correct? - ANSWER-TECH A is correct. An open in the circuit would prevent the blend door's motor operation. A squeal is heard only when the compressor clutch first engages. Technician A says this is caused by a loose serpentine belt. Technician B says this is caused by a worn clutch pulley bearing. Who is correct? - ANSWER-TECH A is correct. A loose serpentine belt will cause a squeal when the clutch first engages. A frozen spot is noticed in the center of the condenser. Technician A says a frozen spot on a component or connection indicates a restriction in the system. Technician B says this is caused by a clogged orifice tube. Who is correct? - ANSWER-TECH A is correct. A restriction in a line or component acts like a metering device and changes the system's pressure. The change in pressure results in a change in temperature. A technician is diagnosing a vehicle's air conditioning system. The vehicle has good engine performance, but the air conditioner is blowing warm air only. A yellow substance is noticed around the evaporator case drip tube. Technician A says this is coolant leaking from the heater core. Technician B says this is fluorescent dye leaking from the evaporator core. Which technician is MOST likely correct? - ANSWER-TECH B is correct. Dye is injected into a system with hard to find leaks. Note that a R-12 system uses one type of dye and a R-134a system uses another. The dye used with R-134a shows up fluorescent yellow. This is brought to light with a special light and glasses.