HVAC Troubleshooting Practice Test

These questions are part of the practice quiz. Start practicing

• Which type of load is associated with the transformer primary in HVAC systems?
• Why is the run capacitor put in the PSC Motors?
• What does a fluctuating temperature indicate in a home?
• What is the most obvious symptom of a short to ground?
• In circuits that have high starting amps, what kind of fuse must be used?
• What condition does low superheat and low subcooling commonly indicate?
• Why is maintaining proper airflow important in HVAC systems?
• Why is regular maintenance important for HVAC systems?
• What is the formula for checking windings on a compressor?
• What does the acronym BTU represent?
• What is the role of the compressor in an HVAC system?
• How can a technician check the function of a thermostat?
• Which of the following indicates that duct cleaning may be necessary?
• If a system is described as "overcharged," what is typically true about both superheat and subcooling levels?
• What is the main function of an air handler in HVAC systems?
• What can occur if an HVAC system operates without a proper refrigerant charge?
• What is the role of a compressor in an HVAC system?
• If a measurement shows no expected resistance, what might that imply?
• In a properly functioning circuit, what should the ohm reading be across an open limit switch?
• Where is the refrigerant stored when pumping down an AC unit?
• During diagnostics for heating, what position should the safeties be in?
• What is the likely consequence of running an A/C unit with a dirty air filter?
• What is the typical resistance measurement that indicates the windings are intact in a properly working motor?
• What problem can arise from not cleaning condenser coils regularly?
• What physical symptom indicates a dirty filter during the cooling process?
• What is the purpose of zoning in HVAC systems?
• What reading would indicate that the pressure switch is functioning correctly?
• What is a likely consequence of over firing a furnace?
• What could cause strange odors from an HVAC system?
• How do non-condensables affect the heat exchange process within an HVAC system?
• How do you calculate superheat in an HVAC system?
• What should be measured at the furnace to check if the thermostat is functioning?
• What type of HVAC system offers the most control over energy usage?
• Why is the transformer primary considered a load in the system?
• When measuring across the transformer secondary, what would indicate a need to test R-C if showing 24 volts?
• What is a common symptom of a failed capacitor in an AC system?
• What is the first event expected to occur after the induced draft motor starts?
• In HVAC troubleshooting, unusual noises from an air conditioner typically indicate what?
• What meter reading of resistance in the winding indicates a short?
• Which type of motor utilizes a run capacitor, start relay, and a start capacitor?
• In HVAC systems, what does an increase in load typically require from the system?
• If there is supposed to be resistance but none is detected, what is this condition called?
• What might increased energy bills indicate regarding an HVAC system?
• What is the purpose of air filters in HVAC systems?
• What type of diagnostic should be run if the induced draft fan motor shows power but is not operating?
• What is a common diagnosis when low subcooling is observed?
• Which condition is indicated by an ohmmeter showing infinite resistance?
• What is the function of a capacitor in a compressor motor?
• When pumping down a refrigeration system, which valve should close first?
• How does a variable speed blower benefit an HVAC system?
• If the ohmmeter shows infinite resistance, what does it indicate?
• Where is the rollout switch typically found in an HVAC system?
• What is one potential consequence of a dirty air filter?
• Which type of motor uses no capacitors or relays?
• If there is a blocked flue, which switch would open?
• What does high superheat suggest in a refrigeration system?
• Which of the following factors can lead to increased pressure in an HVAC system?
• What issue could result in 0 volts in the primary side of a transformer?
• How often is it recommended to service HVAC systems for optimal performance?
• A limit switch is open if what voltage reading is observed across its terminals?
• What does high superheat and low subcooling indicate?
• Which of the following could indicate a draft inducer problem in a furnace?
• If an A/C unit has a low refrigerant charge, how would the compressor amperage be affected?
• If the flame rectification circuit is operating normally, how much current should flow through the flame sensor?
• What is the primary function of a filter drier in an HVAC system?
• What common issue can cause an HVAC system to blow hot air?
• If the pressure switch is stuck closed in a furnace, what would most likely occur?
• If an air conditioning unit is not blowing cool air, what troubleshooting step should be taken first?
• What are common symptoms of low refrigerant levels?
• What is the main purpose of a thermostat in an HVAC system?
• What should technicians monitor to avoid system inefficiencies caused by non-condensables?
• What is the role of the float switch in an HVAC system?
• What characteristic is notable about a short circuit in terms of resistance?
• What impact do non-condensables have on system efficiency?
• What can cause a high Delta T in a furnace?
• What maintenance action can help reduce the risk of mold growth in an HVAC system?
• What causes the burners to dim off after lighting, within 2-3 seconds?
• What type of system modification often leads to energy savings in HVAC systems?
• Which condition is likely to raise the load on an air conditioning system?
• What do high superheat and high subcooling suggest?
• True or False: If the induced draft fan motor has voltage but is not running, the motor is defective.
• What is a common cause for a condenser coil to become dirty?
• If the compressor is running but the fan isn’t, what could likely be wrong?
• What is a challenge associated with using Polyester Oil (P.O.E) in HVAC systems?
• What is the primary benefit of regularly changing HVAC filters?
• What does high amp draw in a motor usually indicate at startup?
• What is one key benefit of regular HVAC maintenance?
• Which temperature reading configuration usually indicates a normal operating condition for an A/C system?
• What does having low superheat usually indicate about the refrigerant charge?
• What might be the cause of excessive humidity in an air-conditioned space?
• What does an increase in pressure due to non-condensables indicate?
• What is a common cause of an air conditioner running continuously?
• During operation, how many motors are typically running in an air conditioning system?
• Which type of electrical load is primarily seen in transformers used in HVAC systems?
• How does high humidity impact HVAC system efficiency?
• What is a sign that an HVAC system may need repair?
• Which of the following is an indication that refrigerant may be low?
• What is the minimum resistance from a motor winding to the compressor housing?
• What role does refrigerant play in an HVAC system?
• Which factor can increase the workload on an HVAC system?
• What does the FLA or RLA rating on a motor indicate?
• What should you check if there is no power (120V) at the induced draft motor?
• What does a dirty condenser coil typically lead to?
• At what part of the AC cycle is the motor current highest?
• Before testing a capacitor with an ohmmeter, what must be done first?
• What can prevent a furnace from igniting?
• What is a common sign of blocked airflow in an HVAC system?
• How can improper slope in a condensate drain line affect an HVAC unit?
• What symptom indicates that a capacitor may be failing?
• Which of the following could be a sign of poor insulation?
• What happens if a thermal expansion valve is stuck closed?
• What condition usually signifies that the compressor is undercharged?
• What condition prevents the pressure switch in the furnace from closing?
• What role does the transformer play regarding load management in HVAC?
• What might a "restriction" in a refrigerant system lead to?
• What is a potential consequence of having a dirty air filter?
• What is a common way to check flame sensor functionality?
• What tool is commonly used to measure gas pressure?
• Why is it important to balance airflow in an HVAC system?
• What happens to motor amperage when the motor starts?
• What does low subcooling signify?
• Under which condition is an air conditioning system likely to operate at its peak efficiency?
• What should you check if your furnace is making loud banging noises?
• True or False: A reading of 24 volts across a limit switch indicates that it is open.
• What indicates a restriction in an AC system?
• Which factor is NOT typically a risk in poorly maintained HVAC systems?
• What type of load is associated with the transformer primary?
• What is the effect of having a 67 degree wet bulb in an HVAC system?
• How many microns is how much the vacuum pump will have to draw down a R-410A system?
• What could be the issue if a compressor runs but does not cool?
• What sound is characteristic of a refrigerant leak?
• What is an indicator of a refrigerant leak?
• What does a blower door test assess?
• How many 120 volt loads are typically present in a heating system?
• What condition is indicated by low superheat and low subcooling?
• Which of the following is a common symptom of a malfunctioning air conditioner?
• What is the typical manifold pressure for natural gas?
• How often should air filters be checked in an HVAC system?
• What does it indicate if an HVAC system is short-cycling?
• How does a dual-fuel system operate?
• What is the purpose of a drain pan in HVAC systems?
• What typically occurs if there is a dirty air filter in an HVAC system?
• What does FLA stand for in HVAC terminology?
• Why is it important to seal ductwork in an HVAC system?
• What is the wet bulb temperature of a standard system indicated by a 67 degree reading?
• Why is the Integrated Fan Control (IFC) located in the blower compartment?
• What can lead to short cycling in an HVAC system?
• What is the first 120 volt load in a call for heat?
• Non-condensables in a refrigerant system cause the pressure to be what?
• Which factor could contribute to high pressures in an AC system?
• What can an improperly sized HVAC unit cause?
• What is an effective way to reduce humidity indoors?
• Which safety device is responsible for shutting off the air conditioning contractor in case of high pressure?
• In HVAC terminology, what does a "starved" system typically refer to?
• What is the importance of thermal expansion valves in refrigerant systems?
• If the limits are normally closed during diagnostics, what should be checked if they are not functioning as expected?
• What symptom indicates a restriction in a metering device?
• What effect do non-condensables have on an HVAC system?
• What happens if moisture is present in the refrigerant system?
• What should the resistance of the start winding be when testing a multi-speed motor?
• What could indicate excessive superheat in a cooling system?
• What is a potential cause of low refrigerant charge in an AC system?
• Which of the following can cause a limit switch to open?
• What issue may arise if the fuse on the IFC board pops while the A/C is running?
• What might cause an air conditioner to short cycle?
• What does a zero ohm reading indicate if measured across a switch?
• What is the state of the relay contacts when the coil is energized?
• What is the function of a condenser unit in an air conditioning system?
• Which symptom may indicate a blockage or restriction in the air filtration system?
• What does a safety switch do in an HVAC system?
• If there is 120 volts at the induced draft fan motor but it is not running, where is the likely problem?
• What could be an effect of an over-firing furnace?
• What component load is being tested when measuring 120V across the heat terminal and neutral terminal?
• What can cause an HVAC system to freeze up?
• How can you identify leaks in your ductwork?
• High outdoor temperatures can lead to what condition in an AC system?
• What is the typical lifespan of an HVAC system?
• What is the normal temperature drop across an A-Coil?
• Low super heat can be caused by which of the following?
• If a hot surface igniter is open, what would it read on an ohmmeter?
• What is a common issue with outdated programmable thermostats?
• What does it mean if the ohmmeter shows zero resistance?
• What condition can result from a faulty thermostat?
• What is combustion analysis used for in HVAC systems?
• What indicates high low side pressure in a refrigeration system?
• A shorted motor ______ could cause the 230 Volt fuses to blow on an AC Unit.
• What could cause a high-temperature rise through a furnace?
• Which symptom would indicate a faulty compressor in an HVAC system?
• What is the primary function of an HVAC system?
• What does a dirty air filter typically lead to in an HVAC system?
• What does low superheat and high subcooling mean?
• Which scenario likely indicates that the induced draft fan is malfunctioning?
• Where should the accurate wet bulb temperature be measured?
• Which symptom might indicate a problem with the blower motor?
• What must be done when checking refrigerant pressure?
• Where is the auxiliary switch typically located?
• If the limit switch is open, what will happen to the furnace?
• What can occur if the air filter in an HVAC system is clogged?
• What ohm reading would suggest that the gas valve is faulty?
• Which type of motor is most commonly used in residential air conditioning systems?
• What does the expansion valve do in an HVAC system?
• What could inconsistent airflow in different rooms indicate?
• What type of device is wired in parallel across the run capacitor to increase the starting torque of a PSC compressor?
• When should you consider upgrading your HVAC system?
• What do high energy bills often indicate in relation to HVAC systems?
• Which of the following symptoms indicates a low refrigerant charge?
• What could be a potential consequence of neglecting HVAC system maintenance?
• The terminal labeled HERM on a dual capacitor is connected to which part of the compressor?
• What is the acceptable resistance from motor windings to the ground?
• Why is regular maintenance critical for HVAC systems?
• What is one common cause of an HVAC system overheating?
• What tool is commonly used to measure air flow in duct systems?
• What might happen if the filters in a system are dirty?
• What does a continuously running blower with no heat indicate?
• Which issue is typically associated with a malfunctioning thermostat in an HVAC system?
• A symptom of a restriction in the liquid line is indicated by which of the following?
• What is a heat pump?
• Which part of the HVAC system helps maintain regulated indoor air quality?
• If the pressure switch closes before the induced draft motor starts, what will happen?
• In a cooling system, what typically happens to the refrigerant by the time it exits the evaporator?
• What tool is essential for monitoring electrical issues in HVAC systems?
• What is needed to check different residential AC systems?
• Why is nitrogen used when brazing in an R-410A refrigerant system?
• Which safety device opens if there is a crack in a heat exchanger?
• Which of the following is a symptom of an overcharge?
• What could cause a heat pump not to perform effectively?
• Why is it important to insulate ductwork?
• Overloads protect motors against which two conditions?
• What causes frost to form on a suction line?
• Which refrigerant is commonly used in air conditioning systems?
• What are signs of electrical issues in an HVAC system?
• What does MERV stand for in relation to air filters?
• What component shuts off the compressor when the thermostat opens?
• How can you maintain optimal indoor air quality?
• What can cause blockages in ductwork?
• What is a routine maintenance task for improving HVAC efficiency?
• What action can help to improve the efficiency of your HVAC system?
• Why is low saturation temperature a concern in refrigeration diagnostics?
• What can cause an AC unit to not cool properly?
• What does a higher SEER rating indicate?