Leak Detection & System Diagnosis Flashcards
7 cards from real EPA 609 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Leak Detection & System Diagnosis flashcards as text
Which tool is specifically designed to detect refrigerant leaks in an MVAC system?
Answer: Electronic leak detector
An electronic leak detector is designed to sense refrigerant vapors and alert the technician to the presence of a leak.
What does a manifold gauge reading of 0 psi on BOTH the high and low sides most likely indicate?
Answer: The system has lost all refrigerant charge
Zero pressure on both sides means the system has no refrigerant remaining, indicating a total loss of charge due to a major leak or prior incomplete service.
UV dye is injected into an MVAC system primarily to:
Answer: Identify refrigerant leaks under ultraviolet light
UV dye circulates with the refrigerant and oil, and when a leak occurs, dye seeps out and glows brightly under a UV lamp, pinpointing the leak location.
An MVAC system that blows warm air while the compressor is running could indicate:
Answer: A refrigerant leak causing low charge
A refrigerant leak reduces system charge, lowering refrigerant flow and heat absorption, so the evaporator cannot cool adequately even though the compressor runs.
Frost or ice forming on the orifice tube or expansion valve in an MVAC system usually signals:
Answer: A restriction or moisture contamination causing a pressure/temperature drop
A restriction or moisture freeze at the metering device causes a dramatic pressure and temperature drop immediately downstream, leading to ice formation.
When using an electronic leak detector, the probe should be moved:
Answer: Slowly along the bottom of hoses and fittings since refrigerant vapors are heavier than air
Most automotive refrigerants are heavier than air and settle downward, so probing slowly beneath hoses, fittings, and connections increases detection sensitivity.
Before performing a leak check on an MVAC system, the technician should first:
Answer: Run the A/C for several minutes to pressurize all components
Operating the system pressurizes the entire refrigerant circuit, making leaks more detectable because refrigerant is forced through any gaps or cracks under pressure.