ASE School Bus

S7 School Bus — HVAC — practice test

Studying for S7 (School Bus — HVAC)? Overhaul Prep has 170 verified S7 questions written to the current task list — in the same formats the real exam uses (direct, Technician A/B, EXCEPT and most-likely-cause). Every answer comes with a written explanation, so you learn why instead of memorising a letter.

170S7 questions

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Sample S7 questions

Straight from the bank — answers highlighted, with the explanation underneath.

In a school-bus A/C system that uses a thermostatic expansion valve (TXV), which component stores liquid refrigerant and holds the desiccant?

Receiver-drier
Accumulator
Orifice tube
Condenser fan

WhyTXV (expansion-valve) systems use a receiver-drier located on the high side after the condenser; it stores liquid refrigerant, filters debris, and its desiccant absorbs moisture.

Technician A says a receiver-drier is used on expansion-valve (TXV) systems. Technician B says an accumulator is used on orifice-tube systems. Who is correct?

Technician A only
Technician B only
Both Technicians A and B
Neither Technician

WhyBoth are correct: TXV systems place a receiver-drier on the high side, while fixed-orifice systems place an accumulator on the low (suction) side.

An A/C system blows warm air, the sight glass shows constant bubbles, and both the low-side and high-side pressures are below normal. The MOST likely cause is:

A low refrigerant charge
A refrigerant overcharge
A restricted condenser
A TXV stuck wide open

WhyLow readings on both sides plus bubbles point to an undercharge/leak; an overcharge or restricted condenser would raise the high side instead.

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