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2 Signs You Might Have a Restricted Expansion Valve

Adjusting Thermostat Valve
Your home's air conditioning system involves a variety of different components, all of which must work together in close coordination in order to meet your cooling needs. If any particular component should cease to behave normally, serious problems may ensue - both for your comfort and for the other mechanical parts of your system.
One common source of problems involves restrictions forming inside of the expansion valve. While you likely don't know much about this component, with the right knowledge you can still pinpoint potential problems it may be experiencing. This article takes a closer look at two signs of a restricted expansion valve.

1. Lack of Cold Air

When it comes to observable signs of air conditioner problems, none could be more straightforward than a lack of cold air. If you've noticed that the air coming through your registers simply isn't as cold as usual, chances are your system has developed a mechanical problem. While a number of issues may be at fault, a restricted expansion valve certainly ranks among them.
The expansion valve lies at the end of your system's liquid line - in other words, the section of tubing connecting your outdoor condensing unit to the indoor evaporator coil. The expansion valve controls the flow of refrigerant into your evaporator coil, ensuring that the pressure in the liquid line exceeds that of the coil.
As refrigerant passes through the valve into the coil, the pressure drop causes it to expand and become colder. This enables the refrigerant to absorb the maximum amount of heat from your home's air. Yet if debris, oil, or other contaminants restrict the flow into the evaporator coil, there simply won't be enough refrigerant to achieve normal cooling.
As the restriction grows progressively worse, you will likely find that the air entering your home becomes less and less cold. Be sure to mention this problem to a trained HVAC technician as soon as possible; otherwise, it may lead to compressor burnouts and other costly forms of damage.

2. Compressor Runs More Frequently

A restriction in the expansion valve doesn't just affect the evaporator coil - it also affects the compressor and the other components that lie downstream from the evaporator coil as well. Insufficient refrigerant means that the pressure inside of the evaporator coil cannot reach its normal levels. This leads to the phenomenon known as compressor starvation.
As its name suggests, compressor starvation involves a lack of refrigerant flow to the compressor. This decreased flow stems from both the reduced amount of refrigerant in the evaporator coil, as well as the reduced refrigerant pressure there. To protect itself from damage, the compressor automatically shuts down when it detects abnormally low pressure.
In the meantime, additional - yet still insufficient - amounts of refrigerant enter the evaporator coil. As this refrigerant sucks up heat and moves out into the suction line, the compressor will turn back on again - only to shut back down once the small amount of refrigerant has been processed.
Technicians can often diagnose a restricted expansion valve by taking a measurement of the pressure in the evaporator coil and/or suction lines. While nobody expects you to take such readings on your own, you  may be able to diagnose the same problem by paying attention to when - and for how long - your compressor runs.
A compressor that seems to run frequently, yet in short bursts offers a strong indication that it is suffering from refrigerant starvation. If you have noticed such behavior in the outdoor portion of your air conditioning system, you should seek professional assistance as soon as possible. Otherwise the strain caused may lead to permanent compressor damage.
For more information about recognizing expansion valve restrictions and other common air conditioning problems, please contact the HVAC professionals at After Hours Heating & Cooling, LLC.