A7 Heating and Air Conditioning


A-7 Heating and Air Conditioning Part 1

Progress:

1. When pressure testing the cooling system on a late model vehicle with a gasoline engine, the pressure on the tester drops but no leaks can be found in the engine compartment. Technician A says that there cannot be an internal leak because the engine oil looks normal, not milky like it would be if coolant were present, and there is no white smoke coming from the exhaust pipe. Technician B starts the engine and, seeing the pressure on the tester gauge increase, says that there is an internal leak, a blown head gasket. Who is correct?

2. All of the following could cause poor heater performance EXCEPT:

3. The high-side pressure in an A/C system is above specifications. All of the following could cause this problem EXCEPT:

4. Technician A says that evacuating an A/C system will remove air and moisture from the system. Technician B says that evacuating an A/C system will remove dirt particles from the system. Who is right?

5. Technician A says that moisture in an A/C system can freeze in the expansion valve and stop the system from cooling. Technician B says that moisture in the A/C system will react with R12 to form an acid that can cause corrosion. Who is correct?

6. When checking recycled refrigerant for excessive air, Technician A says that the container must be stored at 65°F or above for 8 hours out of direct sunlight, before checking the pressure. Technician B says if the pressure is higher than the limit shown for a given temperature, there is air in the tank. Who is correct?

7. At what percentage is refrigerant considered to be pure and safe for recovery?

8. A blower motor only works on high speed. Which of the following answers are MOST LIKELY?

9. During an A/C system performance test, the air temperature at the center outlet duct is warm to slightly cool and the low and high-side pressures on the manifold gauge set are both low. All: of the following could be the cause of these symptoms EXCEPT:

10. A customer complains of low air flow through the instrument panel duct outlets. Which of the following could be the cause?

11. Recovery/recycling equipment must have shutoff valves located within 12 inches of the hoses service ends so that:

[caption id="attachment_1479" align="aligncenter" width="233"] Click image for larger view Full Size View[/caption] 12. The blower motor only works on high. Which of the following could be the cause?

13. During the diagnosis of an ATC system, a trouble code is obtained that references the blend door feedback sensor. Technician A says that the sensor should be replaced. Technician B says that the sensor circuit should be tested. Who is correct?

14. The carpet is wet on the passenger's side of a vehicle. Technician A says this may be caused by a leaking heater core. Technician B says this could be caused by a clogged evaporator case drain tube. Who is correct?

[caption id="attachment_1487" align="aligncenter" width="300"]Click image for larger view[/caption] 15. Technician A says to measure the Sunload Sensor Signal you must use a DVOM and measure its signal voltage changes. Technician B says to use a scan tool and observe the data stream to see the counts change when the light is varied to the sensor. Who is correct?

16. When troubleshooting an ATC (Automatic Temperature Control) system, the system responds when the ambient and in-vehicle temperature sensors are heated and cooled. However, there is no response when the sunload sensor is exposed to a light source. Technician A says that the problem is with the sunload sensor. Technician B says that the problem is with the system's programmer. Who is correct?

17. Vehicles with Dual Zone climate control have a separate ( fill in the blank ) for the passenger side of the vehicle.

18. When filling a container with recycled refrigerant, to what percentage of the container's gross weight rating should it be filled?

19. A vehicle comes into the shop with a complaint of "no cold air". Technician A says to first turn the key off, set the DVOM to DC volts and measure the voltage present at the electromagnet clutch. If there is no voltage present, replace the compressor. Technician B says set the DVOM to DC volts and measure the continuity of the compressor clutch. Who is correct?

20. There is a growling or rumbling noise at the A/C compressor when the system is off and the engine is running. The noise stops when the system is turned on. Technician A says that a bad compressor bearing could be the cause. Technician B says that a bad compressor clutch bearing could be the cause. Who is right?

21. All of the following could cause lower than normal high-side pressure EXCEPT:

22. A customer complains of a foul odor coming from the dash outlets whenever the A/C and blower are on. Technician A says that this is caused by a clogged evaporator drain. Technician B says that this is caused by bacterial growth on the evaporator. Who is correct?

23. The operation of the thermostatic switch depends on the temperature of the:

24. A system with a low pressure on the low side and a heavy frost accumulation on the inlet side of the TXV (Thermostatic Expansion Valve) indicates a:

25. A typical refrigerant identifier can detect all of the following EXCEPT:

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