HVAC Quiz
Questions: 16 · 10 minutes
1. A technician is inspecting a condensate drain connected to equipment where blower pressure could pull air through the drain opening. What is the purpose of a correctly configured trap?
To limit unwanted air movement through the drain and support proper condensate drainage
To increase refrigerant subcooling
To prevent supply air from entering occupied rooms
To regulate voltage to the blower motor
2. Two otherwise comparable air conditioners have different seasonal energy-efficiency ratings. What does the higher rating generally indicate?
The unit always produces colder supply air.
The unit has a physically larger evaporator in every case.
The unit provides greater seasonal cooling output per unit of electrical energy under the rating procedure.
The unit requires no maintenance during its service life.
3. A cooling system rapidly turns on and off even though the thermostat setting is unchanged. Which condition is commonly described as short cycling?
The blower runs continuously at a steady speed.
The system completes long cycles during extreme weather.
The equipment starts and stops in unusually brief intervals.
The thermostat remains off after reaching its setpoint.
4. A system's airflow has gradually weakened, and its disposable return-air filter is visibly packed with dust. What is the most direct likely effect of the dirty filter?
Higher refrigerant flow through the metering device
Faster movement of air through every supply register
A lower electrical supply frequency
Greater resistance to airflow across the system
5. When installing a directional air filter in a typical return path, where should the airflow arrow point?
Toward the return grille and away from all equipment
Upward, regardless of the equipment layout
Toward the nearest exterior wall
In the direction of airflow, generally toward the blower or air-handling equipment
6. What is the general function of a capacitor used with an HVAC motor?
It stores electrical energy and helps create the electrical conditions needed for motor starting or operation.
It converts refrigerant vapor directly into conditioned air.
It removes particles from the return-air stream.
It measures static pressure inside ductwork.
7. In a standard vapor-compression air-conditioning cycle, what happens in the evaporator coil?
Refrigerant rejects heat outdoors and condenses.
Refrigerant absorbs heat from the indoor air and evaporates.
The compressor lowers the refrigerant pressure.
Outdoor air is mixed directly with liquid refrigerant.
8. Before checking resistance on an HVAC electrical component with a meter, what is the appropriate basic safety step?
Leave the circuit energized so resistance is easier to detect.
Touch both probes together while they remain on the live circuit.
Raise the thermostat setting to keep the equipment operating.
De-energize the circuit, follow lockout procedures where applicable, and verify absence of voltage.
9. A supply duct running through a hot, unconditioned attic develops a major leak. During cooling operation, what is the most likely result?
More conditioned air reaches the intended rooms.
Conditioned air is lost to the attic, reducing delivery to occupied spaces.
Return airflow increases by the exact amount lost.
The thermostat automatically becomes more accurate.
10. An air conditioner has a frozen evaporator coil, and inspection finds a severely clogged filter. What should be addressed before evaluating more complex refrigerant faults?
Add refrigerant while the coil remains frozen.
Restore proper airflow by replacing the filter and allowing the coil to thaw.
Close additional supply registers to raise duct pressure.
Increase the thermostat's cooling demand.
11. A cooling system has return air at 75°F and supply air at 55°F. What is the measured supply-to-return temperature difference?
130°F
10°F
55°F
20°F
12. On a humid day, an air conditioner cools indoor air and water drains from its condensate line. The removal of that water is primarily an example of what type of cooling load?
Latent load
Sensible load
Conductive load
Radiant load
13. Why must combustion appliances such as gas furnaces have proper venting?
To add moisture to conditioned air
To carry combustion products, including carbon monoxide, outdoors
To increase return-duct pressure
To keep refrigerant from entering the compressor
14. A heat pump changes from cooling mode to heating mode. Which component redirects refrigerant flow so the indoor and outdoor coils exchange roles?
The reversing valve
The condensate pump
The air filter
The supply-air diffuser
15. Which description correctly distinguishes return air from supply air in a forced-air HVAC system?
Return air goes outdoors, while supply air always stays indoors.
Return air has passed through the evaporator, while supply air has not.
Return air travels from occupied spaces toward the equipment; supply air travels from the equipment back to those spaces.
Return air powers the blower, while supply air powers the thermostat.
16. Indoor air is heated without adding or removing moisture. What generally happens to its relative humidity?
It rises because warmer air always contains more water.
It stays exactly the same because the moisture amount is unchanged.
It decreases because warmer air can hold more moisture relative to its current amount.
It immediately reaches 100 percent.