HVAC Refrigerant Leaks | Heating and Cooling Refrigeration
What you will learn from this article:
1) This article will instruct you on the top reasons and places in the HVAC system for refrigerant leaks.
2) What happens when an air conditioner or heat pump has a low refrigerant charge as a result of a refrigerant leak.
3) What you will see or experience with your HVAC system if you have a refrigerant leak.
4) Why HVAC Contractors do not provide warranties for refrigerant leaks.
5) Making the decision to repair the leak or replace the system.
6) Differences between new refrigerants and old refrigerants.
7) Plenty of in depth related links that allows you to understand the subject better.
Top Reasons for Freon Refrigerant Leaks – Air Conditioner Refrigerant Gas Leaks – Air Conditioning Refrigerant Leaks
HVAC Refrigerant Leaks – There comes a day when the air conditioner stops cooling and you call your local HVAC contractor for air conditioner service and repair. The HVAC service technician arrives and checks the filter and some other things. You see him go to his truck and get some tools and a set of gages while you hope for the best. Ten minutes later he comes back to report to you that your air conditioning unit is low on refrigerant. Now comes the time when you need to understand why the air conditioner needs refrigerant and what to do next?
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)
First of all the air conditioner or heat pump (if you have a heat pump) does not consume Freon or refrigerant.
The system is a sealed system and the air conditioner does not burn or use up refrigerant to make your house cool and/or warm if you have a heat pump. The refrigerant or Freon (Freon is a registered trademark name of Dupont Corporation and is widely used to described the refrigerant in your air conditioner or vehicle air conditioner – typically uses R-134A) in your air conditioner or heat pump is supposed to be locked in a hermetic system and sealed tight. From time to time a leak occurs in the air conditioning system and the unit needs to be charged so that it can continue doing its job of cooling the home or business. As the refrigerant leaks out the system still cools. It actually cools too much. The indoor evaporator coil begins to freeze up because the temperature of the evaporator coil drops below the dew point. This is humidity or moisture in your home or business which passes through the air conditioning (or heat pump) indoor coil (evaporator) for conditioning. The air conditioning system experiences a reduced amount of air flow because of the coil icing up. 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 air flow will come out of the vents.
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)
HVAC Refrigerant Leaks – Causes of Refrigerant Leaks
Here are the reasons why your air conditioner has a Freon or refrigerant leak:
- A shrader valve is leaking Freon and needs to be replaced. There is a tool which 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 tire on your car and 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. Consider yourself lucky if this is the problem because it is easily repaired.
- 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 usually made from 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 can be replaced but the entire system needs to be recovered 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 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 sort of rust preventing paint if a rusty accumulator is found on an air conditioning preventive maintenance check.
- 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 very small copper tubes and over time and through vibration of the system they rub together or rub against another piece of metal and 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 in order to find the leaking capillary tube. When the leak is found the capillary tube can be cut, 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.
- If the air conditioning or heat pump system has any flare connections leaks generally occur at these connection. 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.
- 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 or 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 the coil needs to be replaced. 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.
- Filter dryers are installed in all refrigeration systems and 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 were allowed to get to the components. These filter dryers have screens and desiccant inside them and the outer shell is made if steel. The same problem that occurs with a heat pump accumulator will eventually occur with a filter dryer and a refrigerant leak occurs. These filter dryers are easily replaced 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.
- 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 lawn mower 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 which was pierced by a nail when the roof was replaced. 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.
HVAC Refrigerant Leaks – Refrigerant Leaks Final Advice
That covers the major types of refrigerant leaks which occur with air conditioner and heat pump systems. Depending on the age of the air conditioner or heat pump system and the type of refrigerant leak which occurs may determine whether or not you decide to replace the air conditioner or heat pump system. Many air conditioning and heating service and repair companies will not provide a warranty for refrigerant leak repairs simply because it is possible to repair one refrigerant leak and have another refrigerant leak occur in a different location. It is a decision you must make by weighing the cost of the repairs versus the age of the equipment versus the cost of installing a new coil or air conditioning or heat pump system. If the unit is old and has caused many problems the decision may be easy but it is a big decision so take time and weigh it carefully.
Related Link: It is possible for the air conditioner to cause water damage as a direct result of a refrigerant leak and the system freezing up. (link opens in a new window)
Additionally, caution is advised around refrigerant chemicals including the oil in refrigerant that lubricates the system. Newer refrigerant oils such as the POE’s or Polyol Ester Oil used in HFC refrigerants will absorb moisture including the moisture in your skin causing a burn. If your system is leaking refrigerant it is almost assured that there is oil near the leak area.
Very Small Refrigerant Leak! Freon Found!
More information about HVAC Refrigerant Leaks and refrigeration can be found here.