HVAC Apprenticeship Practice Exam
The main purpose of the accumulator is to: - ANS-Prevent liquid slugs at the compressor
Heat that changes the physical state of a substance without effecting a change in its
temperature is known as: - ANS-Latent heat
The location of the thermal bulb for the TXV on the evaporator affects: - ANS-The amount of
liquid in the evaporator
If the spring is adjusted to increase the superheat, this new setting will: - ANS-Shorten the frost
line
The amount of heat required to raise the temperature of 1 lb of water 1°F is: - ANS-1 Therm
The low pressure oil safety switch: - ANS-Must be reset manually
Suction line oil traps should be installed when the condenser is: - ANS-On the third floor roof
and the evaporator is in the basement
The proper location for an oil separator is between the: - ANS-compressor and condenser
On a TXV, the purpose of an external equalizer is to: - ANS-Compensate for a pressure drop
across the evaporator coil
The approximate boiling point of R-12 at atmospheric pressure at sea level is: - ANS--21°F
The freezing point of water is - ANS-32°F
Crankcase heaters are energized - ANS-When the compressor is of
An accumulator can be located between the - ANS-Evaporator and compressor
On a central air conditioning system, a frosted suction line at the compressor inlet
indicates - ANS-Low back pressure
The normal temperature of the liquid in an air conditioning evaporator is - ANS-35 to 40°F
In an A/C unit, dirty air filters will cause - ANS-Low suction pressure
The reversing valve is commonly used - ANS-On all heat pumps
, If the suction pressure is low and the evaporator temperature high, the cause will be a -
ANS-Starved evaporator
A gage commonly used to measure the pressure in a system while it is being dehydrated is the -
ANS-Micron millimeter gage
When an A/C system is excessively low on refrigerant - ANS-It can become contaminated with
water
There can be nuisance trip outs
The suction line may be too hot to touch
[ALL OF THE ABOVE]
When an A/C system is excessively low on refrigerant - ANS-Low on refrigerant
Dirty air filter
[BOTH A & B]
While the system is operating, the discharge line should be - ANS-At the same temperature as
the crankcase
The most common method used to determine superheat is accomplished by - ANS-Using the
suction gage and a pressure temperature chart and taking a thermometer reading under the
suction line insulation near the gage port
The biggest problem caused by moisture in the refrigeration system is - ANS-Burned out
compressor motors
When used as a drier in the liquid line, silica gel - ANS-Dehydrates water
When is a condensate trap not required - ANS-When the condensate drain is on the discharge
side of the blower
An instrument used to indicate humidity conditions is a - ANS-Hygrometer
Excessive head pressure is often caused by - ANS-Air cooled condenser is plugged
What is the suction gas temperature of R-22 if the pressure is measured as 68 psig - ANS-40°F
With a 5/8" x 5/8" x ¾" tee, what size is the center connection - ANS-¾"
Why is the suction line insulated - ANS-To prevent excessive heat gain
To prevent water damage from condensate on line
[BOTH A & B]
The main purpose of the accumulator is to: - ANS-Prevent liquid slugs at the compressor
Heat that changes the physical state of a substance without effecting a change in its
temperature is known as: - ANS-Latent heat
The location of the thermal bulb for the TXV on the evaporator affects: - ANS-The amount of
liquid in the evaporator
If the spring is adjusted to increase the superheat, this new setting will: - ANS-Shorten the frost
line
The amount of heat required to raise the temperature of 1 lb of water 1°F is: - ANS-1 Therm
The low pressure oil safety switch: - ANS-Must be reset manually
Suction line oil traps should be installed when the condenser is: - ANS-On the third floor roof
and the evaporator is in the basement
The proper location for an oil separator is between the: - ANS-compressor and condenser
On a TXV, the purpose of an external equalizer is to: - ANS-Compensate for a pressure drop
across the evaporator coil
The approximate boiling point of R-12 at atmospheric pressure at sea level is: - ANS--21°F
The freezing point of water is - ANS-32°F
Crankcase heaters are energized - ANS-When the compressor is of
An accumulator can be located between the - ANS-Evaporator and compressor
On a central air conditioning system, a frosted suction line at the compressor inlet
indicates - ANS-Low back pressure
The normal temperature of the liquid in an air conditioning evaporator is - ANS-35 to 40°F
In an A/C unit, dirty air filters will cause - ANS-Low suction pressure
The reversing valve is commonly used - ANS-On all heat pumps
, If the suction pressure is low and the evaporator temperature high, the cause will be a -
ANS-Starved evaporator
A gage commonly used to measure the pressure in a system while it is being dehydrated is the -
ANS-Micron millimeter gage
When an A/C system is excessively low on refrigerant - ANS-It can become contaminated with
water
There can be nuisance trip outs
The suction line may be too hot to touch
[ALL OF THE ABOVE]
When an A/C system is excessively low on refrigerant - ANS-Low on refrigerant
Dirty air filter
[BOTH A & B]
While the system is operating, the discharge line should be - ANS-At the same temperature as
the crankcase
The most common method used to determine superheat is accomplished by - ANS-Using the
suction gage and a pressure temperature chart and taking a thermometer reading under the
suction line insulation near the gage port
The biggest problem caused by moisture in the refrigeration system is - ANS-Burned out
compressor motors
When used as a drier in the liquid line, silica gel - ANS-Dehydrates water
When is a condensate trap not required - ANS-When the condensate drain is on the discharge
side of the blower
An instrument used to indicate humidity conditions is a - ANS-Hygrometer
Excessive head pressure is often caused by - ANS-Air cooled condenser is plugged
What is the suction gas temperature of R-22 if the pressure is measured as 68 psig - ANS-40°F
With a 5/8" x 5/8" x ¾" tee, what size is the center connection - ANS-¾"
Why is the suction line insulated - ANS-To prevent excessive heat gain
To prevent water damage from condensate on line
[BOTH A & B]
