NATE ICE Flashcards Questions with Certified Answers Graded A+

After a vacuum pump has been used, a continuous pressure rise in the system most likely indicates - Answer: existence of a leak after a vacuum has been pulled to 500 microns, a pressure rise in the system, followed by a leveling-off at 1500 microns, most likely indicates the - Answer: presence of a moisture on initial start up of an air conditioning system, the temperature drop measured across the evaporator coil exceeds manufacturer's specifications. this condition most likely indicates - Answer: lack of refrigerant charge the technician is on a spring maintenance check of an air conditioning system. they find the following - head pressure is higher than normal, suction pressure higher than normal, superheat 0 degrees, condenser is clean, outdoor fan operation is normal, subcooling is 25 degrees. which of the following is most likely the problem? - Answer: non-condensibles in the system in a compressor, the internal overload senses the winding temperature and - Answer: amperage in the compressor circuit the function of an external equalizer line for a thermostatic expansion valve is to - Answer: reference the pressure at the evaporator outlet in a fixed orifice air conditioning system, the presence of non-condensables in the system will cause - - Answer: high head and high suction pressures which one of the following could possibly cause a noisy reciprocating compressor? - Answer: broken internal springs two places where superheating occurs in a system are the - Answer: evaporating coil and the compressor if the fan switch on a thermostat sub-base is set to ON and the blower motor is cycling on and off, the most probable cause is - - Answer: motor overload when you are checking for windings of a single-phase compressor with an ohmmeter, the highest ohm reading would be - - Answer: start to run a compressor does not run, although the condenser fan is operating. reading the compressor windings, the measured resistance between r to a is 5 ohms, r to c is open and s to c is open. the problem is due to - - Answer: internal overload being open a compressor with tight bearings will cause the amperage to draw to - Answer: rise above normal which of the following can be caused by insufficient air flow? - Answer: increased compressor failure a correct statement about a hard start kit is that it - Answer: increases starting torque across an r-22 suction line drier, how much pressure drop indicates changing the drier? - Answer: 3 psig which one of the following can be caused by a restricted air filter? - Answer: high superheat which of the following would most likely occur if a crankcase heater fails? - Answer: the refrigerant may not be driven out of the oil a correct statement concerning a relay is that it - Answer: consists of one or more contacts actuated by a solenoid coil the control voltage in an air conditioning system comes directly from - - Answer: the secondary of a step down transformer in a residence, a slight positive indoor air pressure - - Answer: minimizes infiltration which of the following is an important factor when selecting a location for placement of a condensing unit? - Answer: should avoid standing groundwater and roof water runoff which of the following installation steps is necessary to maximize the efficiency of a condensing unit? - Answer: minimum clearances must be maintained around the condensing unit which of the following will contribute to customer comfort and cooling system efficiency? - Answer: select equipment based on load circulation cross breaking sheet metal duct will - - Answer: stiffen the duct and reduce noise the nominal indoor airflow through an air conditioner evaporator coil should be approximately - - Answer: 400 cfm/ton the purpose of the tabs at the top and bottom of the drive cleat is to - - Answer: prevent movement of the drive cleat the sheet metal duct system which has main ducts of equal size is the - - Answer: extended plenum system which of the following is the major benefit of using long radius fittings in a duct system? - Answer: less pressure drop