ESCO A/C

10 pounds of refrigerant passing through a water cooled condenser will lose 20 BTUs of heat per pound. If 10 pounds of water passes through the condenser with an entering temperature of 80°F the temperature of the water leaving the condenser is

100 degrees F

water will vaporize at ________ temperature in a 28 in hg vacuum

100°F

when testing the efficiency of a water cooled condenser, the refrigerant condensing temperature should be approximately _________ higher than the leaving water temperature

10°F

The our 410 a compound gauge reads 124 psi G in the suction line temperature at the condensing unit is 54°F. What is the operating system superheat

12°F

what is the maximum operating pressure setting for an acetylene torch

15 psi G

The R1 30 for a high pressure gauge reads 146 psi G in the liquid line temperature at the condensing unit is 95°F. What is the operating system sub cooling

15°F

if a 30 pound cylinder of reclaimed R 410 a refrigerant has been stored overnight at 70° the pressure in the cylinder should be approximately

201 psig

when testing the efficiency of an air cooled condenser, the refrigerant condensing temperature should be approximately ________ higher than the entering air temperature

30°F

what is generally excepted range for evaporator airflow in CFM's per ton of residential air conditioning

350 to 450

when connecting copper to steal the recommended brazing filler alloy is

45% silver alloy

what is the recommended residential indoor relative humidity for summer

50%

refrigerant R 134a vapor enters the condenser at 124 psi G, 100°F. it leaves as liquid liquid from the condenser subcooled 20°F and the pressure will be approximately

87 psig

if the evaporator pressure does not change when heat is added or removed from the thermostatic expansion valve bulb the problem may be

A faulty bulb or powerhead assembly

in a direct expansion evaporator system the refrigerant enters the evaporator as

A mixture of liquid with some flash gas

0 pounds per square inch absolute is

A pressure which cannot be further reduced

A temperature differential across a filter dryer indicates

A restricted filter dryer

A partially clogged capillary tube can cause

A starved evaporator

A drain trap should be installed on a split system when the

Air handler drain is on the negative air side

The flow rate of a TXV is used in R 410A systems as compared to R22 systems is

Approximately 15% greater

The heat removed from the refrigerant by the condenser is

Both sensible and latent heat.

The temperature rise method for determining airflow is

CFM equals BTU divided by 1.08 x delta T

A decrease in superheat causes the thermostatic expansion valve to begin to

Close

Back seating a two-way service valve results in

Closed service port with normal system flow

moisture in a refrigeration system can cause

Compressor failure

The automatic expansion valve is designed to maintain

Constant evaporator pressure

A customer reports that the residential split system had a compressor replaced last week by another service company. Now the unit is not cooling property. When you arrive and inspect the unit you find that the evaporator seems to be starved for refrigerant. On examining the condensing unit, you find that the liquid line is sweating where it leaves the dryer. This is most likely the result of

Debris from the burned out compressor has clog the dryer

The temperature at which moisture will start to condense from the air is called

Dewpoint temperature

Air or other non-condensable gases in a capillary tube air conditioning system will cause the symptoms

Hi suction pressure and high discharge pressure

A compressor that has a broken valve will cause the symptoms

Hi suction pressure and low discharge pressure

A TXV sensing bulb which becomes detached from the suction line will cause the symptoms

Hi suction pressure in higher than normal discharge pressure

How does a TXV in an operating air conditioning unit react when the bulb is not attached to the outlet or suction line hanging in the air

It always floods the evaporator

If the cut off play is removed from the blower assembly how will this affect blower performance

It would reduce airflow

Which of the following is true of a solenoid valve in a pump down system

Its located before the m.device

While troubleshooting a residential split system the service technician find slow operating pressures in los system amperage draw. This could be an indication of

Low airflow across the evaporator

when a TEV or capillary tube is used as a metering device a low refrigerant charge will cause

Low head pressure

A technician has found an air-conditioning system with a leak in the liquid line. After the line is repaired the system is evacuated in properly recharged. When the system restarted the compressor is noisy and running hot. The most probable cause of the noise is

Low oil in the system

A customer complains that their air conditioning system is running constantly, but no cooling enough. The suction line is very cold in the compressor is sweating. The most likely cause is

Low refrigerant charge

A dirty evaporator in an air conditioning system will cause the symptoms

Low suction pressure and low discharge pressure

A low refrigerant charge in an air conditioning system will cause the symptoms

Low suction pressure and low discharge pressure

in inefficient compressor is usually indicated by ________ Head pressure and ________ Suction pressure

Lower than normal/higher than normal

A thermal electric expansion valve is controlled by

NTC thermistor

mechanical shaft seal is necessary on a

Open Drive compressor

An accumulator is used to

Prevent liquid refrigerant from reaching the comp

after system has been opened and the compressor changed the service technician must

Replace the filter dryer, leak check, evacuate, and charge

bubbles in a sight glass would be an indication of

TXV with an excessive superheat setting

0 pounds per square inch gauge is

The same as atmospheric pressure

the evaporator

Transfers heat from the refrigerated space to the refrigerant

an energy recovery ventilator is

an air to air heat exchanger to recover heat

what type of gauge is used to measure vacuum of 500 microns

an electronic vacuum gauge

if a small air conditioner has only a very low, insignificant refrigerant pressure drop through the evaporator coil, the manufacture may use

an internal equalized thermostatic expansion valve

the standard unit for measuring the quantity of heat in a substance is

btu

solid contaminants such as sludge and carbon from a severe hermetic compressor motor burn out are best removed

by flushing the system and then installing filter dryers in both the liquid and suction lines

The sequential order of steps in the vapor compressions process are

compression, condensation, expansion, vaporization

A liquid line filter dryer should be placed between the

condenser and the metering device

which of the following is the most important consideration in the selection of an evaporator coil. Match the coil to the

condensing unit and the latent/sensible loads

the movement of heat by direct contact is

conduction

A thermostatic expansion valve is designed to maintain

constant evaporator superheat

the movement of heat by way of fluid is called

convection

The first function condenser must perform is to

de superheat

Which of the following represent the right order for the functions of a condenser

de superheat, condenses, sub cools

A low pressure cut off switch is used to

establish a min operating pressure in the evap

there are three basic types of condensers, the air cooled, the water cooled and the

evaporative cooled

The thermostatic expansion valve has three operating pressures

evaporator pressure, spring pressure and sensor bulb pressure

which of the following is not a thermodynamic property of refrigerants

flammability

The clearance space in reciprocating compressor

has an effect on compressor capacity

Which of the following symptoms would be indicated of an oil logged condenser condenser

hi discharge line pressure and low liquid line pressure

A faulty condenser fan motor on an air conditioning system will cause the symptoms

hi suction pressure and high discharge pressure

A refrigerant overcharge in a capillary tube air conditioning system will cause the symptoms

hi suction pressure and high discharge pressure

which of the following is not a symptom of hermetic system that is low on refrigerant

high head pressure

the state of the refrigerant entering the condenser is

high pressure / highly superheated vaoor

A sight glass would be normally located

in the liquid line before the metering device

fan airflow pressures are usually measured in

inches of water column

a liquid to suction heat exchanger is often used to

increase flash gas in the suction line

in overcharge of refrigerant will cause

increase head pressure

And air-conditioning system that is oversize can cause

inefficient dehumidification of the condition space

At a residential service call no cooling complaint, the service technician finds the unit to be completely out of refrigerant. The technician decides to use a trace amount of refrigerant and___in order to pressurize the system

inert gas

when topping off an operating system containing a blended refrigerant

introduce the refrigerant as a liquid into the low side using the throttling valve

scroll compressor move refrigerant by

involute spirals

refrigerant gives up heat when

it condenses

when mounting a thermostatic expansion valve sensor bulb, which of the following is not true

it must be installed lower than the valve body

frost on the suction line indicates

its below 32 degrees

in the evaporator

latent heat is transferred from the refrigerated space to the refrigerant

Heat added to a substance without a rise in temperature

latent heat of vaporization

liquid slugging is

liquid refrigerant in the compressor clearance space

the state of the refrigerant in the suction line should be

low pressure / low temperature vapor

an increase in head pressure causes___refrigerant to flow through a capillary tube

more

compound pressure gauge measures

pressure and vacuum

why must refrigerant in the suction line be slightly warmer than the saturation temperature?

prevent liquid slugging of the compressor

which of the following types of air conditioning compressor is is most energy efficient

scroll

heat which causes a change in temperature of a substance is called

sensible heat

when using an electronica leak detector the sensor probe

should be moved at approximately 1 inch for every two seconds

_________ can be use for a leak detection with all high-pressure refrigerant

soap/bubble solution

A liquid receiver is used to

store liquid refrigerant

Heat added to the refrigerant in a vapor state after the evaporation process is called

superheat

The oil pressure safety switch is operated by _________.

the difference between crankcase pressure and oil pump pressure

Which of the following is not true of a capillary tube metering device

they maintain a constant evaporator temperature

in order to remove as much moisture as possible from a system

triple evacuate the system to 500 µm with a deep vacuum pump

A partially iced over evaporator can be caused by

under charge

in an air conditioning system that uses a thermostatic expansion valve, the temperature of the evaporator outlet will usually be

warmer than the evaporator inlet

In automatic expansion valve is best suited

when the system load remains fairly constant