Written and reviewed by an EPA 608 certified technician · Reviewed July 21, 2026 ·
How this content is made
These original questions show the kind of reasoning the 608 Study Buddy app teaches. They
are not copied exam questions and they are not an official EPA test. Try each question
before opening the answer, then read the explanation: Section 608 questions often change
one detail — appliance type, compressor condition, pressure, or refrigerant state
— and that detail changes the correct action.
Core Sample Questions
1. What change normally occurs in the condenser?
High-pressure vapor becomes high-pressure liquid.
Low-pressure vapor becomes low-pressure liquid.
High-pressure liquid becomes low-pressure liquid.
Low-pressure liquid becomes low-pressure vapor.
Show answer and explanation
Answer: A. The compressor sends a high-pressure, high-temperature
vapor to the condenser. As the condenser rejects heat to the surrounding air or
water, the refrigerant condenses into a high-pressure liquid. Pressure reduction
happens later at the metering device, not in the condenser.
2. Which term means processing used refrigerant until it meets new-product purity specifications verified by chemical analysis?
Recovering
Recycling
Reclaiming
Evacuating
Show answer and explanation
Answer: C. Recovery only removes refrigerant and stores it.
Recycling cleans recovered refrigerant, commonly with oil separation and
filter-driers, for reuse. Reclaiming is the laboratory-grade process that returns
refrigerant to the applicable new-product purity specification. Keeping these three
words separate prevents many avoidable Core mistakes.
3. Why should a recovery cylinder normally be filled to no more than 80 percent of its capacity?
To leave room for liquid refrigerant to expand as temperature rises.
To keep the cylinder light enough to carry without a cart.
To prevent the refrigerant from mixing with cylinder oil.
To make vapor recovery faster than liquid recovery.
Show answer and explanation
Answer: A. Liquid refrigerant expands as it warms. An overfilled
cylinder can become hydraulically full, allowing a small temperature increase to
create a dangerous pressure rise. Technicians use a scale and the cylinder's rated
capacity rather than guessing from pressure alone.
4. Which description matches EPA's definition of a small appliance?
Any appliance used in a residence.
A factory-made, factory-charged, hermetically sealed appliance containing five pounds or less of refrigerant.
Any appliance with a compressor under one horsepower.
Any system containing less than 15 pounds of refrigerant.
Show answer and explanation
Answer: B. The definition depends on how the appliance is made and
charged, not merely where it is used. Household refrigerators, window air
conditioners, dehumidifiers, and vending machines are common examples when they meet
the factory-made, hermetically sealed, five-pound-or-less definition.
5. What makes system-dependent recovery equipment different from self-contained recovery equipment?
It relies on the appliance's compressor, pressure, or heat instead of having its own recovery compressor.
It can be used on every appliance type without restrictions.
It destroys the refrigerant after removal.
It requires refrigerant to be vented before connection.
Show answer and explanation
Answer: A. System-dependent equipment is sometimes called passive
recovery equipment. It has no independent recovery compressor, so it depends on the
appliance or on an external temperature/pressure difference to move refrigerant.
Its use is limited to small appliances and the equipment still must be certified for
the intended recovery method.
6. Using system-dependent equipment on a qualifying small appliance, how does compressor operation affect the percentage-recovery requirement?
Recover 80 percent with an operating compressor and 90 percent with a failed compressor.
Recover 90 percent with an operating compressor and 80 percent with a failed compressor.
Recover 100 percent in both cases.
Compressor condition never matters.
Show answer and explanation
Answer: B. A working compressor helps move refrigerant out of the
appliance, so the percentage requirement is higher: 90 percent. When the compressor
is not operating, the requirement is 80 percent. Exam questions often state the
compressor condition specifically because it is the deciding fact.
7. Why is liquid refrigerant usually recovered before vapor when the equipment and procedure allow it?
Liquid transfer removes most of the charge much faster.
Vapor cannot legally enter a recovery cylinder.
Liquid recovery eliminates the need to recover the remaining vapor.
Liquid recovery always prevents compressor slugging without any controls.
Show answer and explanation
Answer: A. Moving liquid first is faster because it transfers much
more refrigerant mass than vapor recovery. The technician then finishes in vapor
mode to reach the required recovery level. The recovery machine must be configured
for liquid handling; uncontrolled liquid can damage a compressor.
8. Why are zeotropic blends such as R-407C removed from a cylinder as liquid when charging?
Liquid charging helps preserve the blend's intended component proportions.
Vapor charging raises the ozone-depletion potential.
The blend contains no vapor in the cylinder.
Liquid can always be dumped directly into a running compressor.
Show answer and explanation
Answer: A. The components of a zeotropic blend have different
boiling points. Removing only vapor can change the mixture through fractionation.
Taking the blend from the cylinder as liquid preserves its composition. When
charging into the suction side of a running system, the liquid must be metered or
throttled so it does not slug the compressor.
9. Which gas is appropriate for pressurizing a refrigeration system during a controlled leak test?
Oxygen
Compressed air
Dry nitrogen used with a pressure regulator and relief protection
Acetylene
Show answer and explanation
Answer: C. Dry nitrogen is inert and does not add moisture. A
regulator and relief protection are essential because cylinder pressure can far
exceed the system's safe test pressure. Oxygen or compressed air can react
violently with refrigerant oil under pressure and must not be used.
10. What usually happens at a leak in the low side of an operating low-pressure chiller?
Refrigerant sprays outward because every part of the chiller is above atmospheric pressure.
Air and moisture are drawn inward because that part of the chiller operates in a vacuum.
The leak seals itself as pressure falls.
Only oil can pass through the opening.
Show answer and explanation
Answer: B. A low-pressure chiller's evaporator side normally
operates below atmospheric pressure. Instead of pushing refrigerant out, a leak can
pull non-condensable air and water vapor into the machine. That inward leakage is why
purge operation and moisture control are central Type III topics.
11. What is the main job of a purge unit on a low-pressure chiller?
Increase refrigerant pressure before the compressor.
Remove air and other non-condensable gases while minimizing refrigerant loss.
Add moisture so the refrigerant does not freeze.
Replace the rupture disc.
Show answer and explanation
Answer: B. Non-condensables collect in the condenser, raise head
pressure, and reduce efficiency. The purge unit separates and removes those gases.
A purge that runs unusually often is a useful warning that air may be entering
through a leak; the purge treats the symptom but does not repair the leak.
12. Why must water temperature be watched while evacuating a low-pressure chiller?
A deep vacuum lowers water's boiling and freezing behavior, so water can freeze and obstruct evacuation.
Warm water changes an HFC into a CFC.
Water temperature determines the cylinder's hydrostatic-test date.
Cold water permanently raises the refrigerant's GWP.
Show answer and explanation
Answer: A. Water in a low-pressure system can freeze during deep
evacuation. Ice can block passages and make the vacuum appear stable even though
moisture remains. Following the manufacturer's procedure, keeping water from
freezing, and warming the system gently when appropriate help remove moisture
instead of trapping it as ice.
Not affiliated with or endorsed by the EPA. These are independent study questions, not
leaked or reproduced certification-exam items. Rules and testing-provider policies can
change; verify current requirements before relying on them in the field.
