HVAC heating, ventilation, air conditioning & refrigeration system component identification guide: This article lists and explains the function of the basic components of an air conditioning or heat pump systems and provides detailed inspection, diagnostic, and repair advice. We include photographs to assist readers inrecognizing cooling system defects. Example home inspection report language is provided to describe common air conditioning system components and their defects. If your air conditioning or heat pump system has lost its cooling capacity or won't start see REPAIR GUIDE for AIR CONDITIONERS. See How to determine the cooling capacity of air conditioning equipment if the system seems to be working but is inadequate to cool your building. At What are the Parts of an Air Conditioning System and How do Air Conditioners Work? we explained the main parts of an air conditioning system and we described the sequence of steps that make an air conditioner work to cool indoor air.

Below we begin a more detailed A/C system inspection list of air conditioning system components. If your air conditioning system is not working properly, see REPAIR GUIDE for AIR CONDITIONERS The air conditioning system (and heat pump) components introduced here are discussed in detail and are illustrated by photographs and drawings throughout this website using the links at the left of these pages. We explain how to inspect, diagnose, repair, or select, purchase, and install air conditioning systems or their individual parts and components. These components are discussed in detail and are illustrated by photographs and drawings throughout this website using the links at the left of these pages. Above we show two typical compressor/condenser units outdoors. The main internal components of the compressor/condenser unit are listed below: Compressor motor - on residential units this is normally a hermetically-sealed motor-compressor combined in a single unit like the Carrier(TM) unit shown

If a ductless split-system is installed an outside compressor/condenser unit is still required, typically containing the very same functions but perhaps more compact, looking like the Sanyo(TM) unit shown at above right. An air conditioning compressor is a specialized pump which draws refrigerant gas back to the compressor/condenser unit from the in-building air handler and evaporator coil. The compressor compresses the returning low-pressure refrigerant gas to a high pressure (and high temperature) form. In a "split" air conditioning system, multiple indoor evaporator coils and blower units may be served by a single outdoor compressor unit such as the Sanyo unit shown at the top of this page. That unit was handling the compressor/condenser function for two wall-mounted, ductless indoor cooling units, one of which is shown in the right hand photo at "List of Indoor Components" above. Split systems like this do not make use of ductwork. Sketch of the condenser coil courtesy of Carson Dunlop Associates.

Condensing coil receives high pressure refrigerant gas from the compressor and cools this refrigerant gas back to a liquid state.ac power supply design Electrical controls: shut-off switch(es) for service at the unit are provided to permit maintenance and repair of the equipment. ac unit baseCircuit breaker(s) at the electrical panelac units for sale online protect the circuit supplying power to the air conditioning system. Fan an outdoor cooling fan in the compressor/condenser unit moves outdoor air across the condensing coil to cool it and assist in condensing the high pressure, high temperature refrigerant gas back into a liquid. It is this process which completes the transfer of heat through the refrigerant from indoor air to outdoor air

as the compressor/condenser unit compresses and then cools the refrigerant back to a liquid. : these pipes, typically made of copper, include a low-pressure "suction line" which returns low pressure refrigerant gas from the indoor evaporator coil (cooling coil) outlet to the outdoor compressor motor inlet. The high pressure refrigerant line connects the compressor outlet to the outdoor condensing coil inlet (gas) and further connects the condensing coil outlet to the indoor thermal expansion valve which meters high pressure refrigerant into the "low-side" evaporator coil (cooling coil) in the air handler unit in the building. are usually present on the refrigeration lines near the compressor. These valves permit testing the condition of the air conditioning system and permit removal, replacement, or additions to the refrigerant in the system. This photograph of a split system compressor/condenser outdoor unit shows four refrigerant lines and their sets of service ports.

larger diameter copper pipes are the low pressure or suction lines and the smaller diameter pipes are the high pressure lines returning refrigerant to the indoor cooling units. The screw caps visible at the piping connectors where they enter the unit can be removed to provide access to special connecting valves to which the service technician can connect her set of gauges to measure system operating pressures on these lines. unless you're a trainedYou may lose refrigerant or contaminate the system, leading to improper system operation or a costly Continue reading at A/C INSPECTION CHECKLIST - OUTDOOR UNIT or select a topic from the More Reading links or topic ARTICLE INDEX shown below. Or see AIR CONDITIONING & HEAT PUMP SYSTEMS - home Recently, we have received a few questions about the advantages and disadvantages of replacing an older R-22 outdoor unit (partial replacement) versus replacing the whole system (indoor and outdoor components). 

Since R-22 refrigerant and related equipment is being phased out over the next few years as part of the Montreal Protocol regulations to reduce the effect on atmospheric ozone, the decision about whether to stay with R-22 or jump to a new system with R410A is causing some confusion among HVAC consumers.  This is becoming a very common situation and there is really no right or wrong answer as it depends on your particular needs and your personal preferences.  We’ve compiled a few considerations and suggestions for reference. Replacing an R-22 compressor or the outdoor unit (which contains the compressor) is a good, low cost way to get your A/C  system running again without changing the indoor system (which contains the cooling coil, the blower and often is integrated with a gas furnace or other heating system).  This approach can save some money,  if the indoor components are still in good shape and you can find the R-22 outdoor replacement parts along with the R-22 refrigerant.

Many people have decided to do this and many contractors support this approach.  We think this repair will continue to be a viable, low cost repair option, at least through 2016 and maybe longer – as long as parts are available. Some other low cost replacement options should be emerging even after the R-22 availability dwindles.  Many R-22 indoor coils built since 2006 were designed to be compatible with R-410A, which means a homeowner can keep the indoor equipment but upgrade to a newer outdoor unit and metering device. There are some extra parts and steps involved but it should still be lower cost than a total system replacement. Unfortunately, just like with the R-22 outdoor replacement option mentioned above, the overall efficiency of the system typically will not improve when only the outdoor equipment is replaced. For people who are willing to pay a little more, some new, high efficiency retrofits are becoming available in the market.  These should help satisfy homeowners who want the low cost replacement but would also like to reduce their energy bills or address some comfort issues like humidity control, nighttime temperature swings or sound and air quality.