Heating Ventilation and air conditioning Control Systems

Question 1

What type of controls are used by the driver to turn the system on, and adjust air temperature, airflow direction and velocity?
a. active
b. passive
c. supplemental
d. mandatory`

Answer 1

a. active

Question 2

What type of controls may prevent or support system functions?
a. active
b. passive
c. supplemental
d. mandatory

Answer 2

c. supplemental

Question 3

The engine coolant water valve is a passive control that allows the operator to set the amount of hot engine coolant that will pass through the heater core.
True
False

Answer 3

False

Question 4

A 12 volt electromagnetic clutch coil is indicated by a:
a. blue lead wire
b. green lead wire
c. black lead wire
d. white lead wire

Answer 4

c. black lead wire

Question 5

When the air conditioning system contains a fixed expansion tube and an accumulator, the thermostatic switch may be replaced with a:
a. ambient temperature switch
b. high pressure switch
c. clutch cycling switch
d. binary switch

Answer 5

c. clutch cycling switch

Question 6

The pressure settings of the high pressure switch must be adjusted _____________ the settings of the refrigerant’s pressure relief valve or fusible plug.
a. lower than
b. the same as
c. higher than
d. much higher than

Answer 6

a. lower than

Question 7

How many functions does the Trinary switch perform to monitor and control refrigerant pressure inside the air conditioning system?
a. one
b. two
c. three
d. four

Answer 7

c. three

Question 8

What electrical device is used in HVAC systems to control fan or blower motor speed?
a. circuit breaker
b. SPST switches
c. relay
d. resistor

Answer 8

d. resistor

Question 9

A heater system uses _____________ to carry excess engine heat energy to warm the cab air.
a. refrigerant
b. engine coolant
c. engine lubricating oil
d. engine fuel

Answer 9

b. engine coolant

Question 10

List the three outputs of an air conditioning management system.
a_______________
b__________________
c_______________

Answer 10

a. the heater water control valve
b. the fan blower motor
c. the air conditioning system compressor

Question 11

What type of controls regulate the flow of air conditioning refrigerant or heater coolant without driver input?
a. active
b. passive
c. supplemental
d. mandatory

Answer 11

c. supplemental

Question 12

The blower speed switch has three ON positions to control blower fan speed and regulate the HVAC system air velocity, which is measured in:
a. SFM (Square feet per Minute)
b. BTU (British Thermal Units)
c. PSI (Pounds per Square Inch)
d. CFM (Cubic Feet per Minute)

Answer 12

d. CFM

Question 13

A seized open engine coolant water valve will cause the truck cab to remain very warm even when the truck’s air conditioning is operating.
True
False

Answer 13

True

Question 14

The first passive control in the electrical circuit that energizes the compressor electromagnetic clutch is a:
a. thermostatic switch
b. low pressure switch.
c. high pressure switch
d. ambient temperature switch

Answer 14

a. thermostatic switch

Question 15

Refrigerant low pressure sensing switches are used on themostatic expansion valve equipped air conditioning systems as a low ambient temperature protection switches.
True
False

Answer 15

True. Protects the compressor from operating with low refrigerant pressures.

Question 16

The binary switch acts like a ________ switch.
a. low pressure
b. high pressure
c. ambient temperature
d. all of the above

Answer 16

d. all of the above

Question 17

List the two devices used to control refrigerant flow into the evaporator core.
a____________
b____________

Answer 17

a. thermal expansion valve
b. fixed orifice tube

Question 18

List the two types of blower wheels that are used in HVAC systems.
a.____________
b.____________

Answer 18

a. single entry blower wheel
b. double entry blower wheel

Question 19

List the three inputs of an air conditioning input system.
a.______________
b.______________
c.______________

Answer 19

a. high pressure switch
b. low pressure switch
c. evaporator thermostatic switch

Question 20

The door in an HVAC duct system can be controlled by:
a. push or pull cables
b. vacuum motors
c. compressed air motors
d. electric motors
e. all of the above

Answer 20

e. all of the above

Question 21

When the maximum cooling setting is chosen on the control panel, the air conditioning switch is turned to the ______ position. The fresh air door is set on the ___________ position. The temperature setting is turned towards the __________ setting.

Answer 21

on, recirculation, blue

Question 22

When the maximum heating setting is chosen on the control panel, the air conditioning switch is turned to the ______ position. The temperature setting is turned towards the ___ setting.

Answer 22

off, red

Question 23

When the maximum defrost setting is chosen on the control panel, the air flow direction is et towards the _______ position. The air conditioning switch is turned to the OFF position. To remove the mist from the windshield, the air conditioning compressor’s electromagnetic clutch is _______ and the evaporator will cool and _______ the recirculated cab air.

Answer 23

defrost, engaged, dehumidify

Question 24

The manual climate control HVAC system is called a __________ system.

Answer 24

Temperature blend air door

Question 25

The truck’s _______ must be operating if the sleeper compartment is to be heated or cooled.

Answer 25

engine

Question 26

When the cooling function on the control panel is chosen, the electrically controlled refrigerant _________ is opened and refrigerant is allowed to pass through the sleeper compartment’s _________ and into the evaporator core.

Answer 26

Solenoid valve, thermal expansion valve