Previous NATE Heat Pump Service Practice Test 6 Next NATE Heat Pump Service Practice Test 8

NATE_HEATPUMP_SERVICE NEC 2023

NATE Heat Pump Service Practice Test 7

This practice test focuses on the compressor crankcase heater and cold-weather startup risks. You will review refrigerant migration, oil dilution, and oil slugging, plus how to field-check crankcase heater operation. A few questions on COP and dual-fuel systems are mixed in for review.

TOPICS COVERED

NATE Heat Pump Service

How this test works

Read each question carefully

Look for absolute words like always / never — they often distinguish the right answer.

Manage your time

You have 30 min for 30 questions. Skip tough ones and come back.

Progress is auto-saved

Your answers are saved locally — a page refresh won't lose your work.

Review your answers

After submitting you'll see every explanation and your NEC references.

Frequently Asked Questions

Yes — completely free with no signup required. Every question includes a full explanation of the correct answer.

Two: the NATE Core exam plus at least one specialty exam (for example AC Service, Heat Pump Service, or Air Distribution Service). You can take them on the same day or separately.

The Core exam has 50 questions and each installation or service specialty exam has 100 questions. You need 70% on each to pass — 35 of 50 on Core and 70 of 100 on a specialty. Check natex.org for the current format before you book.

NATE certification lasts two years. To renew, you submit 16 hours of continuing education or retake the specialty exam before your certification expires.

No. These are independent practice tests written to match the published NATE exam topics. They are not official NATE exam questions.

Exam Tip: Think of the crankcase heater as protecting the compressor before it even starts. Warm oil resists refrigerant migration; cold oil invites it.

30

Questions

30 min

Time

70%

Pass

Timer starts immediately. Progress is auto-saved.

NATE Heat Pump Service Practice Test 7 — Question List

Question 1: What is the main purpose of a compressor crankcase heater?

To keep the compressor oil warmer than the surrounding refrigerant, reducing refrigerant migration into the oil
To heat the indoor air during defrost
To prevent frost on the outdoor coil
To warm the reversing valve solenoid

Question 2: What can happen if liquid refrigerant migrates into the compressor oil during an off cycle?

The compressor becomes more efficient
The oil can foam when the compressor starts, risking oil slugging
The refrigerant charge increases automatically
The reversing valve locks into heating mode

Question 3: When is a crankcase heater typically most important?

During the hottest days of summer
During the defrost cycle only
During cold weather when the compressor may sit idle for long periods
Only during initial system startup at installation

Question 4: A technician finds a heat pump's crankcase heater has been unplugged all winter, and the compressor was recently replaced due to damage after a cold start. What is the likely connection?

There is no connection between the two events
The crankcase heater only affects cooling mode performance
The compressor damage was caused by the reversing valve instead
Without the crankcase heater, refrigerant may have migrated into the oil, causing oil foaming or slugging damage on startup

Question 5: What does "oil slugging" refer to?

Liquid refrigerant or oil foam entering the compressor cylinders, which can damage internal parts
A buildup of ice on the outdoor coil
A type of refrigerant leak test
A defrost cycle that runs too long

Question 6: Which type of heat pump situation makes a crankcase heater especially useful?

A heat pump that runs constantly with no off cycles
A heat pump that sits idle for extended periods in cold weather
A heat pump used only for cooling in a hot climate
A heat pump with no reversing valve

Question 7: Where is a crankcase heater usually located?

Inside the indoor air handler
On the outdoor fan motor
On or near the compressor housing
Inside the thermostat

Question 8: Why is refrigerant migration into compressor oil more likely during cold weather?

Cold refrigerant has a lower boiling point in general
The compressor runs hotter in cold weather
The reversing valve stays energized constantly in cold weather
In cold conditions, refrigerant tends to condense and settle in the coolest part of the system, which can be the compressor if it is colder than the surrounding refrigerant

Question 9: A technician notices a heat pump's crankcase heater is warm to the touch while the compressor is off, and the system starts up normally without unusual noise. What does this suggest?

The crankcase heater is functioning as intended, helping prevent refrigerant migration
The crankcase heater is malfunctioning and should be replaced
The compressor is overheating
The reversing valve has failed

Question 10: True or False: A crankcase heater runs constantly whenever the compressor is off, in many common designs.

False, it only runs during the summer
True, many designs keep it energized whenever the compressor is not running, especially in cold weather
False, it only runs during defrost
True, but only for 5 minutes per day

Question 11: What is a possible consequence of skipping crankcase heater use in a cold climate?

Higher SEER rating
Improved refrigerant charge accuracy
Increased risk of compressor damage from liquid refrigerant or oil foaming at startup
A shorter defrost cycle

Question 12: A technician is diagnosing a compressor that failed shortly after a cold snap. Besides the crankcase heater, what else should be checked as a possible contributing factor?

The color of the outdoor unit cabinet
The thermostat display brightness
A glossary of refrigerant terms
Whether the system was significantly overcharged or undercharged with refrigerant, which can also stress the compressor

Question 13: Which best describes how a crankcase heater helps protect a compressor?

By keeping the oil warm enough that refrigerant vapor does not condense and dilute it while the compressor is off
By directly cooling the compressor motor windings
By increasing refrigerant pressure artificially
By preventing the reversing valve from energizing

Question 14: A heat pump is installed in a very cold climate but the crankcase heater circuit was wired incorrectly and never energizes. What risk does this create over a typical winter?

No risk, since crankcase heaters are optional in all climates
An increased risk of oil dilution and possible compressor damage on cold-weather startups
A risk of the reversing valve failing to switch modes
A risk of the outdoor fan running constantly

Question 15: Does every heat pump design require a crankcase heater?

Yes, it is required by federal law on all units
No, crankcase heaters are never used on heat pumps
Not necessarily; some designs and climates may rely on other methods to manage refrigerant migration, but many cold-climate systems include one
Yes, but only during the cooling season

Question 16: A crankcase heater failing to energize in cold weather is most similar in risk to which other cold-weather concern?

A dirty air filter reducing airflow
A miscalibrated thermostat display
A clogged condensate drain
Starting a compressor with diluted or foamy oil, risking internal mechanical damage

Question 17: Why might a technician check crankcase heater operation as part of a fall heating season tune-up?

To confirm it will be ready to protect the compressor once cold weather and longer off-cycles begin
To measure the home's cooling load
To calibrate the SEER rating
To reset the defrost timer

Question 18: What happens to compressor oil that has absorbed too much liquid refrigerant?

It becomes thicker and provides better lubrication
It can foam and lose its ability to properly lubricate moving parts when the compressor starts
It automatically boils off before startup
It has no effect on lubrication

Question 19: A crankcase heater is wrapped around or mounted on which specific major component?

The indoor blower housing
The outdoor fan blade
The compressor shell
The reversing valve body

Question 20: A technician is called to a heat pump that short-cycles and makes unusual knocking noises only on the first startup of very cold mornings, but runs fine the rest of the day. What is a reasonable early suspicion?

A defective thermostat display
An oversized outdoor unit
A dirty air filter
A crankcase heater that is not working properly, allowing oil dilution overnight

Question 21: Which weather pattern would most increase the importance of a properly working crankcase heater?

Long, cold nights where the compressor sits off for extended periods
Short, mild nights with frequent compressor cycling
Continuous summer cooling operation
Rainy but warm weather

Question 22: What kind of damage can result from starting a compressor with excessively diluted oil?

Improved compressor efficiency over time
Wear or damage to internal bearings and moving parts due to poor lubrication
A permanent increase in refrigerant charge
A change in the compressor's electrical rating plate

Question 23: A technician measures no voltage at the crankcase heater terminals while the compressor is off in cold weather. What should be checked next?

The color of the refrigerant line insulation
The condensate pump
The crankcase heater circuit wiring, relay, or control board output for that circuit
The size of the return air duct

Question 24: A dual-fuel system's heat pump component sits idle for long stretches in winter while the gas furnace handles most of the heating load below the switch-over temperature. Why might the crankcase heater still matter in this design?

It does not matter since the gas furnace is doing the heating
It only matters if the reversing valve is B-type
It has no connection to compressor protection in dual-fuel systems
The heat pump compressor may still sit idle for long periods, so protecting it from refrigerant migration remains important whenever it is expected to run again

Question 25: Which of these is a simple field check a technician can perform to verify crankcase heater operation?

Feeling for warmth at the heater location, or measuring voltage/current with meters, while the compressor is off
Measuring refrigerant subcooling only
Checking the SEER label on the unit
Listening to the outdoor fan motor

Question 26: Why is it generally not advisable to disable a functioning crankcase heater to save a small amount of energy?

It has no real benefit and can be disabled freely
The small energy savings are generally not worth the increased risk of costly compressor damage
Disabling it improves compressor lifespan
Disabling it is required by manufacturers in most cases

Question 27: True or False: Crankcase heaters are only relevant to heat pumps, never to standard air conditioners.

True, standard air conditioners never use them
True, only heat pumps have compressors
False, some standard air conditioning systems in cold climates also use crankcase heaters for the same oil-protection reason
True, crankcase heaters were invented specifically for reversing valves

Question 28: What is the relationship between crankcase heaters and the compressor's off cycle?

Crankcase heaters only work while the compressor is running
Crankcase heaters turn off automatically the moment outdoor temperature rises above freezing
Crankcase heaters have no relationship to the off cycle
Crankcase heaters are generally most useful and active during the compressor's off cycle, especially in cold weather

Question 29: A technician replacing a failed compressor on a heat pump in a cold climate should also do what regarding the crankcase heater?

Verify the crankcase heater is present, correctly wired, and functioning before returning the system to service
Permanently disconnect the crankcase heater to simplify the system
Remove the crankcase heater and rely on the defrost cycle instead
Replace the crankcase heater with a larger compressor only

Question 30: A crankcase heater draws 70 watts and is energized for 10 hours during a cold overnight period. How much electrical energy did it use during that time?

7 kWh
0.7 kWh
70 kWh
0.07 kWh

EXAM CARD NATE_HEATPUMP_SERVICE

Questions30

Time limit30 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: NEC 2026 (NFPA 70)