Practice question

After replacing a booster pump, the rear heater is still cool. What is a logical next diagnostic step?

Replace the engine thermostat
Assume the new pump is fine and return the bus
Confirm pump rotation/output and check the rear branch for airlock, closed valve, or restriction downstream
Disconnect the rear heater entirely

Answer: C — Confirm pump rotation/output and check the rear branch for airlock, closed valve, or restriction downstream

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