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ASE S7 Air Conditioning Systems & Controls (School Bus) Practice Questions - ASE S7 - Air Conditioning Systems & Controls (School Bus) Certification ExamPractice mode

Question 1 of 25

QUESTION 1 / 25

A school bus A/C system uses R-134a. Which refrigerant identifier and service practice applies?

Choose one answer below.

AR-134a is a non-flammable HFC requiring SAE J2788 recovery/recycling equipment✓BR-134a is a flammable HFO requiring spark-proof tools only✓CR-134a is the same as R-12 and uses mineral oil✓DR-134a requires no recovery because it is environmentally inert✓

0 of 25 answered

A school bus A/C system uses R-134a. Which refrigerant identifier and service practice applies?

Before opening any school bus A/C refrigerant line for service, the technician must first:

A manifold gauge set connected to a school bus A/C system reads high on the low side and low on the high side with the compressor running. The most likely cause is:

The correct way to determine the refrigerant charge for a school bus A/C system is to:

A bus A/C system is being evacuated. The purpose of the vacuum (evacuation) step is to:

Tech A says a school bus with dual (front and rear) evaporators normally holds more refrigerant than a single-evaporator car system. Tech B says the additional rear lines and evaporator increase total system oil requirements. Who is correct?

During an A/C performance test on a school bus, ambient is 90°F and the center duct discharge reads 65°F. This indicates:

Non-condensable air in a school bus A/C system most commonly causes:

Subcooling is best described as the:

Superheat is measured at the:

A school bus A/C system shows frost forming on the liquid line just after the orifice tube and poor cooling. This most likely indicates:

When recharging a school bus A/C system, refrigerant oil should be:

R-1234yf is increasingly used in newer vehicles. Compared with R-134a it is:

A refrigerant identifier should be used before recovery on a bus A/C system to:

A bus A/C system reads high on both the low and high side gauges with poor cooling. The most likely cause is:

A bus A/C system reads low on both the low and high side with poor cooling and the compressor short cycling on the low-pressure switch. The most likely cause is:

The preferred method to leak test a school bus A/C system after repair before recharging is to:

Tech A says a deeper vacuum and longer evacuation time help remove more moisture from a large bus system. Tech B says moisture in the system can combine with refrigerant and oil to form acids. Who is correct?

A pressure-temperature (P-T) chart is used during bus A/C diagnosis primarily to:

After replacing a leaking evaporator on a school bus, the technician should also:

An A/C system with very low refrigerant charge often will not cool because:

A UV dye is added to a bus A/C system to:

On a school bus with a rear A/C unit, weak rear cooling but good front cooling most likely points to:

Which statement about charging a system by weight is correct?

During recovery on a bus A/C system, the recovery machine repeatedly rises back into a positive pressure after shutting off. This usually indicates: