©2016 TTAC Parts Corporation Site Design: MDVC Creative. There are three primary components in a vehicle’s air conditioning system including the compressor, condenser, and evaporator. These parts are connected by tubes and hoses to form a continuous path with two distinct sections: a high-pressure side and a low-pressure side. In order to transfer heat from the vehicle’s interior to the outside air, a chemical refrigerant is circulated throughout the system. In theory, the A/C system accomplishes the same task as the engine’s cooling system, in that both absorb the heat from one area and release it to another (heat transfer). While coolant remains a liquid during the heat transfer process however, refrigerant repeatedly alternates between a liquid and a gas as it circulates throughout the air conditioning system. The compressor is a pump that pressurizes and circulates the refrigerant in the air conditioning system. It is mounted on the front of the engine and driven by the serpentine drive belt or its own individual belt.

The compressor also serves as one of the two junctions separating the high and low sides of the system. Similar to the radiator, the condenser is a large heat exchanger located directly behind the grille. As part of the system’s high side, the condenser is used to liquefy the high-pressure vapor discharged from the compressor. A condenser consists of a series of tubes surrounded by thin fins, which provide a large surface area for heat dissipation. While there are various tubing arrangements used, refrigerant flow is always from top to bottom. Like the condenser, the evaporator is also a heat exchanger consisting of tubes and fins. However, that’s where the similarity ends. Unlike a condenser, which is designed to release large quantities of heat, an evaporator is used to absorb large quantities of heat. An evaporator is also much smaller than a condenser and is part of the system’s low side. Evaporators are located in the air handling case along with the blower. This is a fixed metering device located inside the liquid line between the condenser and evaporator.

The orifice tube is enclosed within a plastic housing and protected by a fine mesh filter. The filter prevents debris from clogging the tube. A variable metering device that varies refrigerant flow based on cooling demand. As demand increases, the valve opens wider to permit more refrigerant into the evaporator. air conditioning outside unit partsOnce the demand has been satisfied, the valve opening is reduced to decrease flow. buy new hvac unitCooling demand is detected within the expansion valve or by a sensing bulb mounted on or near the evaporator.ac unit electrical parts Receiver Drier or Accumulator Depending on the vehicle, the A/C system will either have a receiver drier or an accumulator. Both of these components contain a desiccant, which is a chemical that attracts moisture.

The desiccant serves a vital function, since the combination of water and refrigerant forms corrosive acids. Acids not only reduce A/C performance, they can ultimately destroy the system. The receiver drier and accumulator also serve as temporary holding tanks for liquid refrigerant. Although these two parts serve similar purposes, the receiver drier is connected to the condenser outlet (high-pressure side) and is used exclusively in expansion valve system. In contrast, the accumulator is attached to the evaporator outlet (low-pressure side), and is only found in orifice tube systems. The primary functional difference is that the accumulator is designed to prevent liquid refrigerant from being drawn into the compressor. 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. Please share any additional questions you have in the comments section below. leading supplier of HVAC We specialize in 100% dedicated outdoor air systems and are able to deliver a wide range of options to satisfy ventilation for most building