Practice Test Geeks(310t) Truck and Coach Technician Certification Practice Test
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HVAC and Cab Systems Flashcards

7 cards from real 310T practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 HVAC and Cab Systems flashcards as text

  1. A truck's cab heater produces warm air only at idle but blows cool air at highway speeds. What is the most likely cause?

    Answer: Low coolant level causing air pockets at higher RPM

    Low coolant can cause air pockets that disrupt heater core flow under the increased demand of highway operation.

  2. When recovering refrigerant from a 310T-compliant truck A/C system, the technician must:

    Answer: Use EPA-certified recovery equipment and store refrigerant in approved containers

    EPA Section 608 regulations require certified recovery equipment and approved containers when servicing any stationary or mobile A/C system.

  3. A coach A/C system uses a thermostatic expansion valve (TXV). The evaporator is frosting over. What is the most probable cause?

    Answer: TXV stuck closed restricting refrigerant flow

    A TXV stuck closed starves the evaporator of refrigerant, lowering evaporator pressure and temperature below freezing, causing frost buildup.

  4. What does a sight glass with bubbles during A/C system operation typically indicate?

    Answer: The system is low on refrigerant

    Bubbles or foam in the sight glass during normal operation indicate insufficient refrigerant charge in the system.

  5. A truck cab blower motor runs only on high speed. Which component is most likely faulty?

    Answer: Blower motor resistor or speed control module

    The blower resistor (or PWM control module) provides resistance for lower speeds; if it fails open, only the direct high-speed circuit works.

  6. On a coach with dual-zone HVAC, the rear zone blows warm air while the front zone cools correctly. What should the technician check first?

    Answer: Rear zone blend door actuator and control valve

    In dual-zone systems, independent blend door actuators control each zone; a stuck or failed actuator can prevent the rear zone from receiving cooled air.

  7. What is the purpose of a receiver-drier in a truck A/C system?

    Answer: To store liquid refrigerant and remove moisture and contaminants

    The receiver-drier stores a reserve of liquid refrigerant and contains desiccant to absorb moisture that could damage the system.