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Worksheetsunit 41
Total questions: 25
Worksheet time: 25mins
As a rule of thumb, the air leaving the evaporator will be about ____ than the air entering the evaporator.
10-15° warmer
10-15° cooler
17-20° cooler
17-20° warmer
A service valve can be used to ____.
check the electrical service to the compressor
isolate the refrigerant so the system can be serviced
check the air flow across the evaporator
check the ambient temperature at the condenser
A typical evaporator superheat reading at the evaporator outlet for a central air-conditioning system on a 95°F day would be ____°F.
5-7
8-10
10-12
12-15
On a 95°F day, the R-22 refrigerant pressure on the high side should be about ____ psig
108
182
243
297
The liquid line temperature is used to determine the ____ of a condenser.
superheat
lowside pressure
suction pressure
subcooling
To accurately add refrigerant to a system, a condenser ambient temperature of ____°F should be simulated.
75
85
95
100
The instrument to use to check for a short in the compressor motor winding is a(n) ____.
ohmmeter
ammeter
voltmeter
millimeter
With a rise in outdoor temperature, the head pressure will rise.
true
false
Superheat occurs in the condenser as well as the evaporator.
true
false
The best way to tell if a compressor's discharge line is at the correct temperature is to grab hold of it.
true
false
Subcooling occurs in the evaporator as well as the condenser.
true
false
When checking the electrical circuits of an air-conditioning system, each parallel circuit should be isolated and checked separately.
true
false
If a compressor has a partially shorted winding, it could run for a while, overheat, and shut off.
true
false
Reducing the CFM through the evaporator will cause the head pressure to ____________________.
stay the same, no noticeable change
increase
decrease
rupture the copper tubing
Temperature difference is used to describe the difference in the inlet and _________ temperature of a heat exchanger.
outlet
suction line
expansion valve
superheat
Two types of fixed-bore metering devices are capillary tubes and _________________________.
TXV
orifice
EEV
TEV
Reducing the CFM through the evaporator will cause the amperage draw of the compressor to ____________________.
increase
decrease
stay the same
trip a breaker
Why do we measure temperatures at the evaporator rather than the suction pressure?
It is too hard to reach
The only access port is usually at the outdoor unit
suction pressure is not accurate at the evaporater
because you lose too much refrigerant
Why should a technician visually inspect the equipment and check temperatures before installing gauges?
because there might be a rattlesnake in the outdoor unit
you should always attach gauges and record super-heat and sub-cooling
because bees like to build nests in outdoor units
Installation of gauges may not be necessary and refrigerant is lost whenever gauges are installed and removed.
How would too much refrigerant affect the operation of a system with capillary tubes?
It would raise the head pressure and suction pressure, reduce super-heat, and reduce the system capacity.
It would lower the head pressure and suction pressure, reduce super-heat, and reduce the system capacity.
It would raise the head pressure, lower the suction pressure, reduce supe-rheat, and reduce the system capacity.
There would be no measurable change.
Where is the correct location for a filter-dryer in a split system?
In the liquid line immediately before the metering device
In the vapor line immediately before the metering device
In the liquid line immediately before the compressor
In the liquid line immediately before the condenser
Why is the head pressure raised to 278 psig on an R-22 system to check the subcooling of the system?
This is done to duplicate the conditions where the amount of inside delta-tee was established.
This is not done.
This is done to duplicate the conditions where the amount of sub-cooling was established.
This is done to duplicate the conditions where the amount of super-heat was established.
What is the process that normally begins the electrical troubleshooting of the system?
Begin any electrical troubleshooting by verifying that the power supply is energized and that the voltage is correct.
Begin any electrical troubleshooting by verifying that the power supply is de-energized.
Begin any electrical troubleshooting by verifying that the delta-tee temperature is correct.
Begin any electrical troubleshooting by connecting your manifold gauges.
If a technician finds the circuit protection for an air-conditioning component has been tripped, what should the technician do?
Turn the breaker back on to see if it will stay on.
Perform an amperage check of the compressor section, including the fan motor
Perform a resistance check of the compressor section, including the fan motor.
Perform a voltage check of the compressor section, including the fan motor
Low operating pressure on both high and low side would be caused by...
refrigerant undercharge
refrigerant overcharge
dirty condenser coil
plugged filter-dryer
