NATE Heat Pump Troubleshooting questions and answers

On an air-to-air heat pump system, the suction pressure and discharge pressure are low during the cooling months. What are two possible problems: a restricted indoor metering device and a dirty air filter On an air-to-air heat pump system, the discharge pressure and suction pressure are high during the heating months. What are two possible problems: a dirty indoor filter and noncondensables in the system A service call is made on an air-to-air heat pump system during the winter. When servicing the system, it is found that the outdoor coil has frost buildup and the system is operating on emergency heat. Technician A says that the system might have a defrost problem. Technician B says that the reversing valve might be leaking. Which technician is correct: technician A A service call is made on an air-to-air heat pump system during the winter months. The technician arrives on the job and notices that the discharge pressure is low and the suction pressure is high. What two problems could cause this symptom: a leaking reversing valve and bad compressor valves How can a system be tested to determine if the reversing valve solenoid is leaking internally: A temperature measurement can be taken at the inlet and the outlet of the valve in the heating and cooling mode What component must always be de-energized during the defrost cycle on a heat pump: the outdoor fan When an air-to-air heat pump is in the cooling mode, what can cause a decrease in high-side and low-side pressure: a restricted indoor metering device Technician A says that the check valves in a heat pump system are located in series with both metering devices. Technician B says that the check valves in a heat pump system are located in parallel with both metering devices. Which technician is correct: Both technicians are correct A service technician notices that a check valve needs to be replaced in a heat pump system. Because it is a ball-type check valve, it is critical for him to install the valve: vertically, with the seat on the bottom of the valve After troubleshooting a heat pump system, the technician concludes that the check valve is defective. He connects a recovery system and removes the refrigerant from the unit. He then proceeds to unseat the old check valve and remove it from the system. He cleans the area where the new valve will be installed, places it into position, and brazes it into the system while not protecting the valve. After a thorough evacuation, he starts the system and notices that the new valve is defective. What could have been the problem with the new valve: A heat sink was not used and the valve warped+The valve may have been defective from the factory+The problem was misdiagnosed Technician A says that the auxiliary heaters found on an air-to-air heat pump are used to increase the system's pressure during a defrost cycle. Technician B says that the auxiliary heaters found on an air-to-air heat pump are used to increase supply-air temperature for comfort during a defrost cycle. Which technician is correct: technician B When a heat pump switches into the defrost cycle, it must: remain in defrost until the outdoor coil has reached a predetermined temperature A defrost termination thermostat is commonly located: on the outdoor coil, and opens at 55° F Temperature split refers to: the temperature difference between the air entering a coil and the temperature of the coil Technician A says that the outdoor ambient thermostat commonly de-energizes the compressor during the second stage of heating in an air-to-air heat pump. Technician B says that the outdoor ambient thermostat used with an air-to-air heat pump commonly energizes the auxiliary strip heaters during the first stage of heating. Which technician is correct: Both technicians are incorrect If there is malfunction in a hold-back thermostat that is used with an air-to-air heat pump, how would this affect the system: The system would not stay energized during defrost if the room thermostat is satisfied. This could cause freezing of the outdoor coil. A technician arrives on a service call for an air-to-air heat pump during the heating season. She notices that the system operates normally until the defrost circuit is energized. The system stays in defrost for approximately 15 min when there is no ice or frost buildup on the coil. What could be the problem with the system: The defrost termination switch is stuck closed A technician receives a service call for an air-to-air heat pump. The customer is complaining about insufficient heat during low ambient conditions. Upon arrival to the job, the technician notices that the mechanical heat pump system is operating properly but the auxiliary heat is not operating. What circuit should be checked next: the second-stage heating circuit A technician arrives at a home on a service call for an air-to-air heat pump. After measuring the air temperature over the indoor coil and finding a temperature rise of 35° F, he determines that: the temperature rise is sufficient What are symptoms of an air-to-air heat pump system that has a low charge when in the cooling mode: The low-side pressure will decrease and the indoor coil will be partially frosted A customer calls and says that her air-to-air heat pump system is not cooling properly. Upon arrival, a technician notices that the suction line and compressor has frost buildup. Technician A says that the problem is probably a low charge. Technician B says that it is possibly a dirty air filter. Which technician is more likely to be correct: technician B Name two symptoms that are common to an over-charged air-to-air heat pump system with a system that has a dirty condenser. The discharge pressure increases and the amperage increases