Signs of a Leak in an Air Conditioner or Heat Pump

A leak causes ice to form on the coil and other parts of the air conditioner. Ice buildup on your AC stops it from cooling. The air conditioning system experiences a reduced amount of airflow because of the coil ice buildup. You may notice ice on the copper refrigeration lines, which run to the outside condenser. If you see this, it is important to shut the system off immediately and call your HVAC service company. If the system is left running, the indoor evaporator coil will turn into a block of ice, and no airflow will come out of the vents. Reduced airflow is a symptom of a refrigerant leak.

Related In-Depth Link: An example of what you will see and expect if your air conditioner has a refrigerant leak and freezes up . (link opens in a new window) Related Link: On a refrigerant temperature-pressure relationship chart or PT chart the less refrigerant in the system the colder the system. When the temperature of the coil drops below the freezing, the moisture in the air freezes to the coil. (link opens in a new window)

Side Note: Freon® is a registered trademark name of Chemours, a Dupont spin-off Corporation. Freon® is widely used to describe the refrigerant in your air conditioner and your vehicle air conditioner. Your vehicle typically uses R-134A, which is different than what is in home air conditioners and heat pumps. Technically, it is inaccurate to refer to refrigerant as Freon®. Freon® is a name used to describe R-22 made by Chemours (Dupont spin-off). R-22 is currently being phased out with the final phase-out date set for 2020.

Air Conditioner Leaking Freon® - Causes of Refrigerant Leaks - HVAC Refrigerant Leaks

The most likely leaks for a central air conditioner system can be anywhere and caused by various things. Air conditioning units, as well as heat pumps, are mechanical systems with moving parts. Here are the reasons why your air conditioner has a Freon or refrigerant leak:

Leaking Shrader Valve Heat Pump Accumulator Leak Capillary Tube Leak Flare Connections Evaporator or Condenser Coils Filter Dryers Line Set

1

Leaking Shrader Valve

A Shrader valve is leaking Freon and needs to be replaced. There is a tool that can be used to change this Shrader valve without having to recover the entire amount of refrigerant from the system.

These Shrader valves look like the little valves in your car tire. They hold the refrigerant in the system and allow the technician to access the system to test the pressures or to charge the system if necessary. These Shrader valves are necessary, and sometimes the rubber seals deteriorate, or the Shrader valve gets stuck and allows Freon or refrigerant to leak out of the air conditioner system.

Shrader valves are located in or near the condenser unit but can also be in the indoor unit, the air handler. Consider yourself lucky because this problem repaired easily.

2

Heat Pump Accumulator Leak

If you have a heat pump heat pumps have accumulators. Accumulators are necessary for the heat pump system to provide heat in the winter and protect the compressor from liquid slugging. Accumulators are steel, and after a few years, they begin to rust. These rust holes allow Freon or refrigerant to leak out of the heat pump system. The heat pump accumulator replacement is possible, but the recovery of the refrigerant is necessary, and a new accumulator installed.

The new accumulators sold on the market today are also made of steel and will eventually leak after rusting occurs in the future. It is hard to say what the average life expectancy of an accumulator is and depends on the quality of steel used to make the accumulator, so the time varies on when the accumulator will leak.

To prevent this from occurring in the future with a new accumulator or new heat pump it is not a bad idea to spray the accumulator with some rust preventing paint upon discovery of a rusty accumulator on an air conditioning preventive maintenance check.

3

Capillary Tube Leak

A capillary tube is leaking on the inside evaporator coil or if you have a heat pump on the outside heat pump condensing unit. These capillary tubes are tiny copper tubes, and over time and through the vibration of the system, they rub together or rub against another piece of metal.

A hole appears on the capillary tube, and Freon or refrigerant leaks from the air conditioning or heat pump system. These leaks can be difficult to find because dis-assembly of the system is necessary to find the leaking capillary tube. Upon discovery of a leak, a cut is made in the capillary tube, the hole for the capillary tube reamed, and another larger piece of copper tubing soldered over the capillary tube.

This does not apply to capillary tubes which connect metering devices to thermostatic expansion valve (TXV) bulbs. These damaged TXVs need to be replaced and do not contribute to leaking Freon from the system.

4

Flare Connections

If the air conditioning or heat pump system has any flare connections, leaks generally occur at these connections. Sometimes these flare connections can easily be repaired while other times the flare fitting and connection has to be replaced and remade completely to prevent future leaks in your AC unit.

5

Evaporator or Condenser Coils

The indoor or outdoor air conditioning or heat pump coil is leaking and needs repair or replacement. Most of the time, the leaks in the coils (whether they be outside or inside coils for an air conditioning or heat pump system) occur at the u-tubes. These are bends in copper at the end of the coil.

There is a tube sheet made of sheet metal which holds the coils together, and over time, and through vibration, the u-tube part of the coil rubs against the tube sheet, and a refrigerant leak occurs. Sometimes this can be easily repaired, but other times, replacing the coil is necessary. Depending on the age of the unit, indoor and outdoor coils are available for replacement.

The problem with leaks near the tube sheet is when the technician uses heat to repair the leak in the coil, the heat loosens other parts of the coils, and another leak could occur. It will take a very good technician who knows how to braze very well in order to repair this type of refrigerant leak.

6

Filter Dryers

Filter dryers are installed in all refrigeration systems. They are necessary for absorbing minute amounts of moisture in the system and for filtering trash before it gets to key components, which could be damaged or plugged if the trash was allowed to get to the components. These filter dryers have screens and desiccant inside them and the steel outer shell.

The same problem that occurs with a heat pump accumulator will eventually occur with a filter dryer, and a refrigerant leak occurs. Replacing the filter dryers are easy but only after recovering the entire amount of refrigerant or pumping the entire amount of refrigerant contained in the air conditioner or heat pump system into the condenser using the pump down method.

7

Line Set

The line set which carries refrigerant back and forth from the condenser to the evaporator coil has been pierced or damaged. Damage can occur from a lawnmower or someone tripping over the line set. Additionally, line sets generally run in voids inside walls and ceilings just below the roof.

I once had a line set that was pierced by a nail on a roof repair. The refrigerant took a year to leak out before the air conditioner was no longer functional and the customer required an HVAC professional to troubleshoot and repair the air conditioner system.