Fan cycling controls are pressure switches that sense high-side pressure, or temperature controls that sense liquid line temperature that turn the fan off when the condensing pressure-temperature falls, and on when the pressure-temperature reaches the upper setting on the fan cycling switch.
What is the function of a condenser fan cycle control?
Cycling of the condenser fans
helps regulate the condens- ing temperature
. Using this approach, as the ambient drops the fans are taken off-line either one at a time, or in pairs.
What is the proper cut in setting for a fan control?
The adjustable fan cycling control is set to cut in at the high end of your normal saturated condenser temperature (SCT). This may typically be
between 120 and 130 degree SCT
. The cut out is adjusted for the lowest end of normal operating SCT.
What causes a condenser fan to cycle on and off?
What is low pressure switch?
A low-pressure switch is
connected to the suction, or “low” side of the system to sense suction pressure
. When the pressure in the system exceeds the high pressure switch setting, the switch will open circuit the compressor clutch and the compressor will stop circulating refrigerant.
Does AC pressure switch control fans?
The pressure switch monitors the A/C loop's high pressure level, it enables or disables the compressor according to two pressure thresholds.
One additional circuit controls the cooling fan
, it secures the condensation process by forcing the air flow through the condenser.
What device can be used to control the speed of a condenser fan motor?
P315PR direct-mount pressure-actuated controllers
are designed for speed variation of electronically commutated (EC) condenser fan motors. Varying the fan speed controls the system's head pressure, for optimum performance throughout the year. The controllers can be used in non-corrosive refrigerant systems.
What is the purpose of a low ambient control?
Low ambient control.
When refrigeration systems are exposed to low ambient conditions, the condensing pressure (head pressure) will fall
. If the head pressure gets too low, the metering device will not have enough pressure drop across it to operate properly.
What is the minimum condensing temperature for standard refrigeration units?
What is the minimum condensing temperature for standard refrigeration units?
90 degrees F
. What are three common methods of head pressure control during low ambient?
What is a Lac valve?
LAC-4 – The valve designation LAC stands for Low Ambient Control. The LAC-4 is
a three way modulating valve that responds to discharge pressure
. As shown in Figures 1 and 2, the discharge pressure bleeds around the pushrod to the underside of the diaphragm. The discharge pressure opposes the dome pressure.
What problem occurs when the condenser fan short cycles?
What problems occurs when the condenser fan short cycles ?
The fan motor can be damaged
. After the vapor has been condensed to a liquid, what are 2 causes for the liquid to flash back into a vapor before it reaches the metering device ? A rise in temperature or a fall in pressure.
How does the receiver ensure that only 100 liquid refrigerant enters the liquid line?
How does the receiver ensure that only 100% liquid refrigerant enters the liquid line?
By means of a dip tube
.
When should my condenser fan run?
Normally the condenser fan motor should be running
when the compressor is running
. Power ( 115 volts AC ) to the motor and it is not running is a bad fan motor.
Why does my AC turn on and off every 5 minutes?
An AC system may turn on and off repeatedly due to
dirty, broken, or failing parts or for various other mechanical or electrical reasons
. The term short cycling refers to when an AC system's cooling cycle terminates prematurely only to turn on again after a short time.
Why is my AC outside unit fan not turning on?
If the fan doesn't start running,
you may have a bad fan motor
. If you have difficulty getting the blades to turn, there may be debris wrapped around the fan axle, or the motor bearings may be dirty or jammed.
How does AC pressure switch work?
AC Pressure Switch Function
One monitors the high-pressure side, while the other is evaluating the low-pressure aspects
. The low-pressure switch ensures that the pressure never drops too low. This problem is caused when a leak occurs.
What does AC high pressure switch do?
A high pressure switch and a low pressure switch are used to
protect the compressor and refrigeration circuit
. The system for an inoperative outdoor motor and/or a dirty/restricted outdoor coil is monitored by the high pressure switch.
What are two types of pressure switches?
- Mechanical (electromechanical)
- Electronic (solid state)
Are pressure switches normally open or closed?
There are two types of pressure switches:
normally open (NO) and normally closed (NC)
. The open/closed nomenclature refers to the electrical contacts in the switch.
How does a low pressure AC switch work?
The AC pressure switch is a safety switch mounted on the upper and lower sides of the air conditioning system. When the pressure goes up too high or falls too low (on the side of the system where the sensor is mounted),
the switch turns off the compressor to avoid damage
.
Is AC low pressure switch normally open or closed?
While there are a number of different switches used (depending on the system design), two of the most common are the low-pressure and high-pressure cutout switches. These switches are
normally closed
, providing power through the compressor-control circuit when the system is operating at safe pressures.
What is fan speed controller?
A fan speed controller
controls the voltage across the fan and therefore indirectly controls its speed
. A fan speed regulator actually measures and regulates the speed of the fan using its tachometer.
How can I control my AC fan speed?
- You can use TOROIDAL TRANSFORMER to supply lower voltages to the fan in order to reduce speed of the fan.
- It does not cause damage to fans by providing a lower voltage to fans.
- You can use a diac and triac to control supply voltages.
What would the symptom be if an air-cooled condenser had two fans and one stopped running?
What would the symptom be if an air-cooled condenser had two fans and one stopped running? There would be an
increase in head pressure
as the refrigerant warmed and expands.
What would happen if the evaporator pressure becomes too low?
What could happen if the evaporator pressure becomes too low?
Moisture will freeze on the evaporator surface restricting air flow
. On a vehicle equipped with front and rear A/C dual evaporator system, the front evaporator cools properly, but the rear evaporator is warm.
Do I need a low ambient kit?
A Low Ambient Kit is
intended to maintain system pressures at normal levels should indoor cooling be required when outdoor temperatures are low
. The kit works by slowing the condenser fan to maintain head pressure by varying the air flow through the outside evaporator coil.
What effect will low ambient temperatures have?
Recovery during low ambient temperatures will;
slow the recovery process
. Ozone depletion in the stratosphere is what type of problem? Global.
