Deck 12: Coach Air Conditioning

Question 1

What state is the refrigerant in when it exits the condenser on its way to the receiver tank?

A) Superheated vapor
B) Subcooled liquid
C) Supercooled liquid
D) Subcooled vapor

Answer 1

B

Question 2

What component does not store refrigerant during a low side pump down?

A) The main evaporator
B) The subcooler
C) The condenser
D) The receiver tank

Answer 2

A

Question 3

Whenever the main liquid line solenoid is energized which evaporator will be operating at all times?

A) The drivers evaporator
B) The main evaporator
C) The left parcel rack evaporator
D) The right parcel rack evaporator

Answer 3

B

Question 4

The thermostatic expansion valve controls the flow of refrigerant into the evaporator based upon:

A) Evaporator inlet temperature only
B) Evaporator outlet temperature and pressure
C) Evaporator outlet pressure only
D) Evaporator inlet temperature and pressure

Question 5

Which of the following will not cause a bus compressor to have lower than normal suction pressure?

A) TXV superheat setting is to low
B) Broken TXV or capillary tube broken
C) Refrigerant overcharged
D) Plugged filter drier

Question 6

What component is designed to create less flash gas to increase refrigeration efficiency and performance?

A) The condenser
B) The evaporator
C) The thermostatic expansion valve
D) The subcooler

Question 7

What is the source of heat that causes the refrigerant to boil in the evaporator?

A) The ambient air
B) The heat of compression
C) The heat from the interior of the bus
D) The heat from the bus engine

Question 8

What can result if moisture is allowed to enter into the air conditioning system?

A) Moisture can freeze in the system causing a blockage.
B) Refrigerant oil can for sludge the can cause blockages.
C) Acid can form causing copper plating of the bearing surfaces and eventual compressor failure.
D) of the above can result from too much moisture entering the system.

Question 9

What component is used to turn a bus compressor on or off?

A) The drive pulley
B) The electromagnetic clutch
C) A centrifugal clutch
D) An over-running clutch

Question 10

What valve must be front seated while the air conditioning is running in order to perform a low side pump down?

A) Discharge check valve
B) Suction service valve
C) The discharge check valve
D) The receiver outlet valve

Question 11

What is requires in order to calculate the superheat setting of a bus air conditioning system?

A) Evaporator outlet temperature and evaporator inlet temperature pressure and a refrigerant pressure temperature chart.
B) Evaporator outlet temperature, evaporator inlet pressure and a refrigerant pressure temperature chart.
C) Condenser inlet temperature, evaporator inlet pressure and a refrigerant pressure temperature chart.
D) Evaporator outlet temperature, suction pressure and a refrigerant pressure temperature chart.

Question 12

What is the purpose of the discharge line check valve?

A) To restrict the flow of refrigerant in the discharge line.
B) To prevent the migration of liquid refrigerant back into the compressor in the heat mode.
C) To prevent the migration of liquid refrigerant back into the compressor in the cool mode.
D) To prevent the migration of liquid refrigerant back into the compressor in the off mode.

Question 13

Which of the following could cause high compressor discharge pressure?

A) Refrigerant overcharged
B) Dirty condenser coil
C) Incorrect fan rotation
D) Any of the above could cause the high compressor discharge pressure.

Question 14

What procedure would you use if you wanted to repair the main liquid line solenoid valve and replace the filter drier without removing the entire refrigerant charge?

A) Compressor pump down
B) Discharge valve pump down
C) Low side pump down
D) A parcel rack pump down

Question 15

What is the minimum size of vacuum pump required to evacuate a bus air conditioning system?

A) 2 CFM
B) 3 CFM
C) 4 CFM
D) 5 CFM