AC Troubleshooting Test (Complete) Flashcards
A reading of infinite resistance across a coil of a contactor is an indication that the coil…?
* Is shorted and should be replaced
* Has an open and should be replaced
* Has the proper resistance reading and should be left on the contactor
* Cannot be determined from the information provided
Had an open and should be replaced/
A reading of line votage across a compressor overload indicates that the…?
Overload is in the open position
High superheat is not cause by…?
System Undercharged
Overfeeding metering device
Restriction in system
Blower speed too high
Overfeeding Metering device
A refrigerant undercharged on a system with an automatic explansion valve is indicated by…?
*___subcooling and ____ superheat
Low subcooling and high superheat
Low superheat can be caused by all of the following except…?
* Improper evaporator airflow
* System undercharged
* Dirty air filter
* Overfeeding metering device
System undercharged
Which of the following is true regarding the difference between the supply and return air temperature?
* At a return air temperature of 75F with 50% RH, the difference will ideally be between 17 to 20 degreees.
* At humidity levels higher than 50% the diffrence will be somewhat lower 17 to 20 degrees
* At humidty levels lower than 50%, the difference will be somewhat greater than than 17 to 20
* All of the above
At a return air temperature of 75F with 50% RH the difference will ideally be between 17-20 degrees.
On a standard effeciency R22 Air conditioning system operating on a 95 degree day, the head pressure will be about —– PSIG and the condenser saturation temperature will be about —— Degrees fahrenheit
* 278PSIG, 125F
* 243PSIG,115F
* 226PSIG,110F
* 211PSIG,105F
278PSIG,125F
30F Temperature Differential
What of the following is true regarding the evaporator pressure and temperature?
* If the system load is high, the evap temp will increase and the evap pressure will decrease
* If the system load is low, evap temp will increase and the evap pressure will decrease
* If the system load is high, the evap temp and pressure will both increase
* If the system load is high, the evap temp and pressure will both decrease
If the system load is high, the evap temp and pressure will both increase
Pressure and temp are married when you add more heat to the evap.
On a air conditioning system, the refrigerant typicalls boils at a temp that is________ degrees lower than return air temp.
* 15
* 20
* 35
* 50
35
the difference between your evap SST and Return air temperature
A reading of 0 Resistance across the coil of a contactor is an indication that____
* The coil is shorted and should be replaced
* The coil is open and should be replaced
* There is no power being supplied to the contactor coil
The coil is shorted and should be replaced
A reading of 0 volts across the overload of a compressor indicates that____
* The overload is in the open position
* The overload is in the closed position
* There is no power being supplied to the compressor circuit
The overload is in the closed position
or
There is no power being supplied to the compressor circuit
A refrigerant overcharge can be indicated by_______
* High evaporator superheat
* High condenser subcooling
* Low suction pressure
* High condenser fan amp draw
High condenser subcooling
High superheat can be caused by…?
* An overfeeding metering device
* A refrigerant undercharge
* A dirty filter
* All of the above
A refrigerant undercharge
Low superheat can be caused by…?
* An underfeeding metering device
* A refrigerant undercharge
* A dirty air filter
* None of the above
A dirty air filter
If the return air is about 75F with 50% humidity, the temp of the supply air will be in the range from ———degrees?
* 17F to 20F
* 25F to 35F
* 55F to 58F
* 65F to 75F
55F to 58F
On a standard efficiency R22 air conditioning system operating on a 85F day, the head pressure will be about——–PSIG and the condenser Saturation temp will be about—– degrees
* 278,125
* 243,115
* 226,110
* 211,105
243,115
If the load on an air conditioner drops, the evaporator coil temp will…?
* Increase and the low side pressure will increase
* Decrease and the low side pressure will decrease
* Increase and the low side pressure will decrease
* ecrease and the low side pressure will increase
Decrease and the low side pressure will decrease
The difference between evaporator coil temp and the return air is usually about…?
* 5F
* 15F
* 25F
* 35F
35F
