EPA 609 Leak Detection & System Diagnosis 3

Question 1

Which type of leak detector offers the highest sensitivity for finding very small refrigerant leaks?

Accepted Answer

Heated diode (infrared) or heated element electronic detector

Answer

Soap bubble solution

Answer

Nitrogen pressure test only

Answer

Visual inspection under sunlight

Question 2

A vacuum pull-down test is used in MVAC service to:

Accepted Answer

Verify the system holds a vacuum, confirming no leaks remain after repair

Answer

Check compressor discharge pressure

Answer

Measure refrigerant charge weight

Answer

Test the pressure relief valve operation

Question 3

Under EPA Section 609, if a technician discovers a leak during MVAC service, the required action is:

Accepted Answer

Recover the refrigerant and repair the leak before recharging

Answer

Continue service and note the leak for the customer to address later

Answer

Add extra refrigerant to compensate for the expected loss

Answer

Tag the vehicle and refuse all service until a certified shop handles it

Question 4

What does a restriction in the HIGH side of an MVAC system (such as a plugged liquid line drier) typically cause?

Accepted Answer

High pressure upstream of the restriction, low pressure downstream toward the metering device

Answer

Low pressure on the high side, high pressure on the low side

Answer

Equal pressures on both sides of the system

Answer

Compressor short-cycling due to low suction pressure only

Question 5

Nitrogen is sometimes used during leak testing of MVAC systems because:

Accepted Answer

Nitrogen is an inert, dry gas that safely pressurizes the system for leak checking without adding moisture

Answer

Nitrogen reacts with refrigerant to identify leak points chemically

Answer

Nitrogen dissolves refrigerant leaks and seals them temporarily

Answer

Nitrogen is required by EPA 609 as the only approved leak test gas

Question 6

After completing refrigerant charge on an MVAC system, system performance is most accurately verified by:

Accepted Answer

Measuring vent outlet temperature and comparing manifold pressures to specification charts

Answer

Confirming the compressor clutch engages at least once

Answer

Listening for unusual compressor noise only

Answer

Checking that both high and low side pressures are equal

Question 7

A refrigerant identifier should be used before recovering refrigerant from an MVAC system primarily to:

Accepted Answer

Detect refrigerant contamination or incorrect refrigerant type that could damage recovery equipment

Answer

Measure the exact refrigerant charge weight remaining in the system

Answer

Determine whether the compressor oil needs replacement

Answer

Test the system for moisture content before evacuation