HVAC II Final Exam Review| 50 Questions | Correct Answers.

IF a heat pump works normally in the heating mode but will not provide cooling or a defrost mode, which component is most likely defective? - ANSWER Reversing valve Air-to-air heat pumps produce heat by - ANSWER extracting heat from the outdoor air and transferring it to the indoor air In addition to the reversing valve, the other major difference between a heat pump and a cooling only system is - ANSWER heat pumps require two metering devices In the cooling mode, the reversing valve is normally - ANSWER energized When a heat pump is operating in the heating mode, the refrigerant bypasses the - ANSWER indoor coil metering device In the reverse cycle heating mode, - ANSWER the indoor coil acts as a condenser Refer to figure RQ01. What happens in the cooling mode if the discharge temperature switch fails to close? - ANSWER The outdoor fan does not run Refer to figure RQ02. If the outdoor thermostat is not closed and this system is in the heating mode, a likely symptom would be - ANSWER less supplemental heat available Refer to figure RQ03. Defrost is initiated by - ANSWER defrost control Which of the following conditions is not common and proper during the defrost mode? - ANSWER The compressor shuts off If a heat pump blows cool air into the conditioned space during the colder parts of the heating season, a possible cause is - ANSWER that the supplemental electric heaters are not on during defrosting During dual fuel heat pump operation, the compressor and furnace burner can operate together ___. - ANSWER during periods of defost Refer to figure RQ04. The variable-speed indoor fan motor receives low voltage input signals by the way of ___. - ANSWER a 16-pin connector If a heat pump will not initiate defrost and you suspect the reversing valve, the quickest way to verify your suspicion is to - ANSWER see if the reversing valve switches when the operating mode is changed Low primary voltage at the control circuit transformer may cause - ANSWER relay chatter