Practice Test Geeks(LEC) Locomotive Engineer Certification Practice Test
← All LEC Flashcard Decks

Heating, Ventilation & AC Flashcards

7 cards from real LEC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Heating, Ventilation & AC flashcards as text

  1. Under FRA regulations, if a locomotive's heating system fails during cold weather operations (below 32°F), what is generally required?

    Answer: The locomotive must be removed from service or the heating system repaired before continued operation

    FRA regulations generally require that locomotives with inoperative heating systems be removed from service in cold conditions to protect crew safety.

  2. Which refrigerant is most commonly used in modern locomotive HVAC systems due to its lower environmental impact compared to older alternatives?

    Answer: R-134a or R-1234yf

    R-134a (and the newer R-1234yf) replaced ozone-depleting R-12 and R-22 in modern locomotive AC systems due to their lower environmental impact.

  3. An engineer notices the AC system is short-cycling — turning on and off rapidly. What does this typically indicate?

    Answer: Low refrigerant charge or a malfunctioning pressure switch

    Short-cycling often results from low refrigerant charge or a faulty pressure switch causing the system to trip off prematurely.

  4. How does outside air intake quantity typically change when a locomotive travels through an area with poor air quality (e.g., smoke, dust)?

    Answer: Outside air intake is reduced or switched to recirculation to limit contaminant entry

    In areas with poor outdoor air quality, reducing outside air intake or switching to recirculation limits the introduction of contaminants into the cab.

  5. What is the purpose of the high-pressure cutout switch in a locomotive AC system?

    Answer: It shuts down the AC compressor if refrigerant pressure exceeds a safe limit to prevent component damage

    The high-pressure cutout switch protects the compressor and system components from damage by shutting down the AC if discharge pressure becomes dangerously high.

  6. During a crew change, the oncoming engineer finds the cab temperature is 95°F in summer heat. What HVAC action should be taken first?

    Answer: Activate maximum cooling with fresh air intake to rapidly reduce cab temperature before departure

    Activating maximum cooling with fresh air intake quickly purges hot air and reduces cab temperature to a safe level before departure.

  7. What effect does a dirty or clogged cabin air filter have on locomotive HVAC performance?

    Answer: It restricts airflow, reducing system efficiency and increasing blower motor strain

    A clogged cabin filter restricts airflow through the system, degrading both heating and cooling performance and stressing the blower motor.