Hvac Controls & Electrical Schematic
Symbols, Air 135 Exam Study Guide
Questions And Answers With Verified
Solutions 100% Correct!!!
A defrost control that works off of elapsed time is a
ANSWER✔✔ Defrost Timer.
A way to sense temperature using a thermistor is
ANSWER✔✔ Solid-state.
The pressure or temperature at which you set the control is the
ANSWER✔✔ Set point.
What are 3 reasons that a system might go off because of the high-pressure
switch?
ANSWER✔✔ 1. Broken condenser fan
2. Condenser is dirty
3. Unit is overcharged.
The temperature or pressure at which the unit turns on is called
ANSWER✔✔ The cut-in.
The temperature or pressure at which the unit turns off is called
ANSWER✔✔ The cut-out.
A way to sense temperature using a sensing bulb is
ANSWER✔✔ Liquid expansion.
A switch that will shut the unit off if there is a drop in oil pressure is the
ANSWER✔✔ Oil failure (or safety) switch.
A way to sense temperature using a bimetal is
ANSWER✔✔ Metallic expansion.
, The amount you can adjust the controls is called the
ANSWER✔✔ Range.
A switch that will shut the unit off if the pressure gets too high
ANSWER✔✔ High pressure switch.
The difference between set point and control point is called
ANSWER✔✔ The offset.
The __________________________ adjustment controls the temperature
difference (same word as in study guide)
ANSWER✔✔ Differential.
Range adjustments provide for ___________________________ temperature
or pressure in an automatic system
ANSWER✔✔ Minimum and maximum.
The oil pressure safety switch is used on systems of what size?
ANSWER✔✔ Large systems.
The oil pressure safety switch is only used on a compressor that has a
_______________?
ANSWER✔✔ Oil pump.
HP (high pressure) of the oil pressure safety switch connects to
ANSWER✔✔ The high side pressure of the oil pump (oil pump discharge
pressure).
LP (low pressure) of the oil pressure safety switch connects to
ANSWER✔✔ The low side of the compressor (compressor crankcase low
side pressure).
It is the job of an oil pressure safety switch to protect
ANSWER✔✔ Against the loss of oil pressure.
This allows the compressor and oil pump to get up to running pressures
ANSWER✔✔ Delay relay.
Symbols, Air 135 Exam Study Guide
Questions And Answers With Verified
Solutions 100% Correct!!!
A defrost control that works off of elapsed time is a
ANSWER✔✔ Defrost Timer.
A way to sense temperature using a thermistor is
ANSWER✔✔ Solid-state.
The pressure or temperature at which you set the control is the
ANSWER✔✔ Set point.
What are 3 reasons that a system might go off because of the high-pressure
switch?
ANSWER✔✔ 1. Broken condenser fan
2. Condenser is dirty
3. Unit is overcharged.
The temperature or pressure at which the unit turns on is called
ANSWER✔✔ The cut-in.
The temperature or pressure at which the unit turns off is called
ANSWER✔✔ The cut-out.
A way to sense temperature using a sensing bulb is
ANSWER✔✔ Liquid expansion.
A switch that will shut the unit off if there is a drop in oil pressure is the
ANSWER✔✔ Oil failure (or safety) switch.
A way to sense temperature using a bimetal is
ANSWER✔✔ Metallic expansion.
, The amount you can adjust the controls is called the
ANSWER✔✔ Range.
A switch that will shut the unit off if the pressure gets too high
ANSWER✔✔ High pressure switch.
The difference between set point and control point is called
ANSWER✔✔ The offset.
The __________________________ adjustment controls the temperature
difference (same word as in study guide)
ANSWER✔✔ Differential.
Range adjustments provide for ___________________________ temperature
or pressure in an automatic system
ANSWER✔✔ Minimum and maximum.
The oil pressure safety switch is used on systems of what size?
ANSWER✔✔ Large systems.
The oil pressure safety switch is only used on a compressor that has a
_______________?
ANSWER✔✔ Oil pump.
HP (high pressure) of the oil pressure safety switch connects to
ANSWER✔✔ The high side pressure of the oil pump (oil pump discharge
pressure).
LP (low pressure) of the oil pressure safety switch connects to
ANSWER✔✔ The low side of the compressor (compressor crankcase low
side pressure).
It is the job of an oil pressure safety switch to protect
ANSWER✔✔ Against the loss of oil pressure.
This allows the compressor and oil pump to get up to running pressures
ANSWER✔✔ Delay relay.
