Air Conditioning Certification Practice Test Answers and Questions, Exams of Electrical and Electronics Engineering

Download Air Conditioning Certification Practice Test Answers and Questions and more Exams Electrical and Electronics Engineering in PDF only on Docsity! Air conditioning Certification practice test with Correct Answers. What is the movement of heat through space called? - Correct answer Radiation A refrigerant release heat when - Correct answer It condenses Why is it desirable for refrigerant in the suction line to be slightly superheated? - Correct answer To insure liquid refrigerant does not enter the compressor A 30 pound cylinder of reclaimed R-22 refrigerant has been stored over night at 70 degrees F. What should be the approximate pressure in the cylinder? - Correct answer 121 psig 14.7 psia( pouds per square inch absolute) is - Correct answer Approximately 0 PSIG What is the main fuction of an air condition condenser? - Correct answer To remove heat from the refrigerant Refrigerant R-134a vapor enters the condenser at 124 psig, 100 degrees F. It leaves the condenser at 80 degreesF. What will be the approximate pressure? - Correct answer 124 psig (the pressure should not change entering or leaving the condenser) Which of the following CANNOT be used as a low ambient temperature control? - Correct answer Crankcase regulating valve When testing the efficiency of a (10 seer are lower) air cooled condenser, the refrigerant condensing temperature should be no more than_______ higher than the entering air temperature - Correct answer Approximately 30 degrees F When testing the efficiency of a water cooled condenser, the refrigerant condensing temperature should be no more _____ higher than the leaving water temperature. - Correct answer 10 degrees F What does a temperature differential across a filter-drier indicate? - Correct answer Restricted filter-drier Which of the following symptoms would be indicative of an oil logged evaporator? - Correct answer Reduce heat transfer through the walls of the coil When using an electronic leak detecto, the sensor probe - Correct answer should be moved at approximately 1 inch per second Before a vapor / compression system is opened for service - Correct answer the refrigerant must be recovered using approved equipment What is the minimum vertical drop from the outlet of the condensate drain pan to the inlet of the P trap when the evaporator is ahead of the blower? - Correct answer 3 inches The temperature rise method of determining air volume CFM is mostly used with a/an; - Correct answer electric resistive heat air handler What is a sling psychrometer used to measure - Correct answer wet and dry bulb temperature A compressor is operating with a discharge pressure of 235.3 psig and a suction pressure of 35.3 psig. What is the compression ratio (pumping ratio)? - Correct answer 5:1 (235.3+14.7=250) and (35.3+14.7=50) so 250/5=5 What method does hot gas bypass refer to? - Correct answer Capacity control IF a TEV sensing bulb has lost of its charge, What effect would this have on the air conditioning system - Correct answer It would cause the low side pressure to decrease What is a crankcase heater used to prevent? - Correct answer Refrigerant migration to the compressor crankcase during the off-cycle. The type of compressor that allows access to the internal components is the _______. - Correct answer reciprocating semi-hermetic What do water cooling towers require? - Correct answer Periodic de- scaling When a compressor service valve is in the cracked position, which port is closed? - Correct answer None are closed . When the service valve is in the cracked position all ports are open Why must an oil separator be kept warm? - Correct answer To prevent refrigerant from condensing in the separator during the off cycle. Which part of the system stores refrigerant until it is needed in the evaporator: - Correct answer the receiver Which part of the system prevents liquid from entering the compressor: - Correct answer the accumulator A split-system air conditioning unit has: - Correct answer the compressor and condenser connected by a refrigeration line set to the metering device and evaporator In a sealed system, as the pressure increases: - Correct answer the temperature increases A room thermostat should be mounted - Correct answer near a return-air grill What is the purpose for insulating a suction line: - Correct answer to prevent condensation from forming A typical evaporator superheat reading at the evaporator outlet for a central air-conditioning system on a 95°F day would be ____°F. - Correct answer is: 10-12 As a rule of thumb, the air leaving the evaporator will be about ____ than the air entering the evaporator. - Correct answer The Correct answer is: 17-20° cooler With a rise in outdoor temperature, the head pressure will rise - Correct answer True refrigerant overcharge - Correct answer - high operating pressures, refrigerant undercharge - Correct answer - low operating pressures blocked/dirty filter - Correct answer - low operating pressures, non-condensable gas in system - Correct answer - high operating pressures, defective condenser fan motor - Correct answer - high operating pressures, defective evaporator fan motor - Correct answer - low operating pressures, dirty condenser coil - Correct answer - high operating pressures If the metering device malfunctions and gets stuck in the closed position, the compressor could overheat. - Correct answer 'True'. Superheat occurs in the condenser as well as the evaporator. - Correct answer True' If a compressor has a partially shorted winding, it could run for a while, overheat, and shut off. - Correct answer 'True' When would it be beneficial for a technician to pump a system down before servicing? - Correct answer when the thermostatic expansion valve needs to be changed To accurately add refrigerant to a system, a condenser ambient temperature of ____°F should be simulated. - Correct answer 95 Why does a high efficiency condenser operate at much lower head pressures? - Correct answer The high efficiency condenser has a larger surface area and uses modern alloy surfaces and fins. This allows the condenser to reject heat much more rapidly. This brings temperature down and reduces the head pressure. What type of metering device do you find on a high efficiency system? - Correct answer High efficiency systems use a TXV rather than a fixed bore device. How do you determine EER? - Correct answer It is the amount of output in BTUH divided by the number of input in Watts. 36000 Btuh / 4000 W = EER of 9 How do you determine EER? - Correct answer It is the amount of output in BTUH divided by the number of input in Watts. 36000 Btuh / 4000 W = EER of 9 What is SEER? - Correct answer It is an efficiency rating system that takes includes the startup and shutdown cycles. When measuring high voltage, what are the parameters for 115V and 208V/230V? - Correct answer It is ± 10% of the rated voltage. For 115V, that would be 104V - 126V. For 208V/230V that would be 187V - 253V What is the approach temperature? - Correct answer Also known as temperature split. It is the difference in temperature between heat exchange mediums. Example would be the temp difference between the indoor coil and the return air for an AC system. What is a service valve? - Correct answer It is a valve that can be used to isolate the system for service. It is usually manually operated. Why should you use a short gauge hose on the high side? - Correct answer If you used a long hose, the amount of liquid refrigerant in the hose may be enough to affect the system charge and gauge readings. What should be the highest discharge line temperature? - Correct answer It should not exceed 220°F.