< Continued from page 1 Components of Automotive Air ConditioningYour air conditioning system is made up of a compressor, a condenser, an evaporator (or drier), refrigeration lines and a couple of sensors here and there. Compressor: This is the heart of your a/c system. The compressor is what takes the refrigerant (the gas) and pressurizes it so it will cool the air. It's run by an engine belt. The compressor also has an electrically operated clutch that turns the compressor on and off as you demand more cool air. Condenser: The condenser is like a miniature radiator, usually mounted at the front of the car right next to your big radiator. Sometimes the condenser will have its own electric cooling fan, too. The hot, compressed air passes through the condenser and gets lots cooler. As it cools, it becomes a liquid. Evaporator: The evaporator is another little radiator that does just the opposite task as the condenser. As the super-cool liquid is passed through its tubes, air is forced through and gets really cold, right before it hits your face.

As it warms up again, the refrigerant starts turning back into a gas. Thermal Expansion Valve: You don't always want to freeze your toes off, so the a/c system has a valve that controls the flow of super-cool refrigerant to the evaporator. This way you can regulate how cold the air blowing on you gets. There are a few types of valves in use these days, but they all do the same thing. Drier or Accumulator: The drier, also known as the receiver-drier, is sort of the safety catch for your system. The compressor is only supposed to compress the gas form of your refrigerant. However, there's always a chance that some liquid could make it back that far. The drier catches this liquid before it can damage your compressor. Since even the tiniest leak or careless installation can introduce water moisture to the system, the drier absorbs this chemically, using what's called a dessicant (similar to that packet of "DO NOT EAT" that comes with electronics). The drier also has a filter that catches any gunk that might be in there.

That's pretty much the whole story! Different systems also have sensors here and there to tell it pressure and temperatures, but they are specific to a make and model of vehicle. If you need to do some work on your car or truck's AC system, be sure to have a repair manual specific to your vehicle.Package air conditioner is a bigger version of the window air conditioner. However, unlike window air conditioner or PTAC units, it has a higher cooling or heating capacity and is usually able to cool an entire house or a commercial building. The nominal capacities ranges from 3 tonne to 15 tonne. The conditioned air are transferred to the space to be conditioned through ducting which is usually hidden in the ceiling and wall of the building. The unit is placed outside the house, a special room in a building or even on top of a roof. This unit is factory assembled and skilled technicians are needed to install this type of unit.Protection devices such as High/Low pressure switch, overload relays for all motors, water flow and air flow switches are included in the units.

The compressor have winding protection thermostat built into the winding to disconnect the circuit in the event of overheating.There is an interlocking circuit with the evaporator fan motor starter to ensure that the compressor can only start if the fan motor is running. how to tell what size ac unit i haveThis self contained unit is assembled in a casing where all the air conditioning componenets are housed. how to size a room ac unit Rooftop Air-Cooled Package Air Conditioner.Package Air Conditioner Condenser TypeThe condenser used in a package air conditioner can be air-cooled or water-cooled type. cover for ac unitAir-cooled type is usually for capacity below 5 tonne and water-cooled for capacity above 5 tonne. The capacity of air-cooled type is lower than that of water-cooled condenser using the same compressor.

The water-cooled type can be completely factory assembled, tested and charged with refrigerant before being installed in the field. This is advantages because less man power is needed in the field to do the installation hence cost saving.The air-cooled type cannot be factory assembled or charged as the laying of refrigerant piping, pressure testing, charging and evacuation have to be carried out in the field.In the air distribution, centrifugal fans are usually provided at the evaporator side which can develop higher static pressure. The higher the static pressure, the better the air throw to the room is. Air distribution is done through ducts and grills. The air quantitites are usually in the range of 10-11.3 cubic meter/min (350-400 cfm) per tonne.In critical application such as computer room which need higher rate of air flow, higher capacity fans with air flow up to 550 cfm are provided. This usually need to be factored in during the design of the system.In some units, two independent refrigeration systems are included in the package.

In this case, the cooling coils have a common tube sheets though the two systems are independent. The tubes of the coil are entwined. Two separate water-cooled condensers or a condenser with an internal partition that forms two independent condensers are used. The water side is common to both the independent condenser portions.It is a common practice to have one compressor running all the time with the other compressor control by a single-stage thermostat. In this case, the capacity can be controlled either to 50% or 100%. However, newer units have two-stage thermostat that can control the capacity from 0%, 50% or 100%. Back To Package Air Conditioner Home PageWhat you will learn from this article Air Conditioner Condenser Electrical Components:Brief description of air conditioner condenser electrical componentsCode requirements for the condensing unit feeder circuit, fuse box, and wire running to the condenserWiring inside the condenserDescription of various electrical components inside the condenserLots of resource and related links to help you learn more.

Air Conditioner Condenser Electrical ComponentsThere are many electrical components inside an air conditioner unit. From relays to contactors to electric motors and wiring. It all works together to make your air conditioner run smoothly. It is almost like a ballet and the air conditioner sequence of operation follows a specific sequence to work properly.For the purpose of brevity, the focus of this article will be on the condenser and the electrical components in an air conditioner condenser. From the disconnect box on the wall next to the condenser all the way through the control panel and into the components we’ll cover all the various electrical components and how they work together to make your air conditioner work.Related Link: Read more about condensing units (opens in a new window) Air Conditioner Condenser Electrical Components - Fuse Box or DisconnectThe fuse box or disconnect for the air conditioner condenser is required by NEC code and should be within reach of the condenser.

The fuse box should have a way of protecting the circuit for the condenser. Despite the breaker in the main panel, an air conditioner disconnect box needs to be fused or have some sort of trip protection in case an electrical problem occurs inside the condenser with an electrical component. The protection should be sized according to the ampacity of the air conditioner as rated by the manufacturer.This information is available for unit ampacity and fuse size on the nameplate on the side of the condenser. The wire supplying the air conditioner unit should be sized according to NEC tables at 125% of RLA or Run Load Amps which is also rated on the unit plate with other data.NEC and Electrical DataThis information is available for unit ampacity and fuse size on the name plate on the side of the condenser. The wire supplying the air conditioner unit should be sized according to NEC tables at 125% of RLA or Run Load Amps which is also rated on the unit plate with other air conditioner nomenclature.

The fuse should be sized no larger than 175% of RLA of the unit and with exceptions can be raised to no more than a maximum of  225% of RLA. This allows for the fuses to be able to overcome the start amps of the unit. Start amps are usually referred to as LRA or Locked Rotor Amps which can far exceed the RLA for the first split second when the unit starts.Refer to Article 440.22 of the NEC for more information on this but those are the basics for disconnects, fusing, and wiring for the disconnect. On a side note - the fuses used in a fused disconnect should be dual element fuses and often referred to as slow blow fuses. These fuses are designed to handle the inrush current on equipment start-up.Related Link: Read more about the NEC and HVAC including Branch Circuit Conductor Sizing  for air conditioner and heating equipment (opens in a new window)Air Conditioner Condenser Electrical Components - Wiring and Components in the CondenserWiring inside the condenser can be classified as control wire and line voltage wire.

The control wire in residential air conditioner systems originates at the thermostat and is 24 volts. This controls all the relays and contactor(s) in the air conditioner and runs through any safety or limits in the condenser. What type of safeties can be in the condenser? Refrigeration pressure switches are commonly used in the higher rated equipment. Some manufacturers put high-pressure refrigeration switches in all their condensing units. In higher end condensers you will also find low-pressure refrigeration switches.These switches will trip the system shutting it down because extreme high-pressure and low-pressure in the condenser can cause serious issues and it is better to shut the system down as it needs repair to correct the problem. Additionally, an air conditioner condenser can have a delay switch in the control circuit to prevent the condenser from short cycling in various cases. Short cycling is bad for the electrical components in the air conditioner condenser especially the compressor which can be irreparably harmed if short cycling occurs.

Resource Link: Learn about control circuits for air conditioning and heating systems (opens in a new window)Other HVAC Electrical ComponentsThe line voltage wiring carries the voltage and amps to the fan motor and the compressor. It is very important that all the connections in the line voltage circuit are very tight. Lose connections cause problems with build up of heat and corrosion on the connections. Eventually, the heat and the corrosion will cause the wire to break off from the connection altogether and failure of the compressor or fan motor will occur. In the line voltage circuit inside a condenser of a residential air conditioner are a contactor, run capacitors for the compressor and condenser fan motor, and the condenser fan motor and the compressor.If the system requires a start capacitor the start capacitor for the compressor will also be in the circuit for the air conditioner condenser. There will be a potential relay in the circuit that will also be wired to line voltage as the potential relay uses line voltage and not control voltage.

Resource Link: Learn how start capacitors help motors start when extra torque is needed (opens in a new window) Air Conditioner Condenser Electrical Components - Crank Case HeatersMany air conditioners and heat pumps have crankcase heaters to prevent migration of refrigerant to the compressor crankcase in low ambient temperatures outside. The crankcase heater is designed to protect the compressor from liquid refrigerant on start up. Liquid does not compress therefore liquid can and will damage mechanical components inside the compressor. The crankcase heaters keeps the oil in the crankcase hot to prevent the liquid refrigerant from damaging the compressor through liquid slugging.Some crankcase heaters are controlled with a temperature switch so when the temperature outside drops the crankcase heater is switched on while other crankcase heaters remain on all the time with no switching at all except the breaker or disconnect for the condenser.In the event of a power loss, many manufacturers recommend letting the air conditioner sit for 24 hours after power is restored.