Heating Ventilation and air conditioning Control Systems Flashcards
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`
a. active
What type of controls may prevent or support system functions?
a. active
b. passive
c. supplemental
d. mandatory
c. supplemental
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
False
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
c. black lead wire
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
c. clutch cycling switch
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
a. lower than
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
c. three
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
d. resistor
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
b. engine coolant
List the three outputs of an air conditioning management system.
a_______________
b__________________
c_______________
a. the heater water control valve
b. the fan blower motor
c. the air conditioning system compressor
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
c. supplemental
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)
d. CFM
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
True
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
a. thermostatic switch
Refrigerant low pressure sensing switches are used on themostatic expansion valve equipped air conditioning systems as a low ambient temperature protection switches.
True
False
True. Protects the compressor from operating with low refrigerant pressures.
The binary switch acts like a ________ switch.
a. low pressure
b. high pressure
c. ambient temperature
d. all of the above
d. all of the above
List the two devices used to control refrigerant flow into the evaporator core.
a____________
b____________
a. thermal expansion valve
b. fixed orifice tube
List the two types of blower wheels that are used in HVAC systems.
a.____________
b.____________
a. single entry blower wheel
b. double entry blower wheel
List the three inputs of an air conditioning input system.
a.______________
b.______________
c.______________
a. high pressure switch
b. low pressure switch
c. evaporator thermostatic switch
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
e. all of the above
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.
on, recirculation, blue
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.
off, red
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.
defrost, engaged, dehumidify
The manual climate control HVAC system is called a __________ system.
Temperature blend air door
The truck’s _______ must be operating if the sleeper compartment is to be heated or cooled.
engine
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.
Solenoid valve, thermal expansion valve
