HVAC Refrigerant Leaks | Heating and Cooling Refrigeration 5/5 (3)

HVAC Refrigerant Leaks | Heating and Cooling Refrigeration

What you will learn from HVAC Refrigerant Leaks:
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.

HVAC Refrigerant Leaks | Heating and Cooling Refrigeration
New Clean Evaporator Coil for a Heat Pump

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:

  1. freon leaksA 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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 HVAC 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.

HVAC Refrigerant Leaks – Related Links

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)

HVAC Refrigerant Leaks – Conclusion

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.

High Performance HVAC

HVAC Refrigerant Leaks – Leaking Freon

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9 thoughts on “HVAC Refrigerant Leaks | Heating and Cooling Refrigeration

  1. Why would you not just change both lines! Not much more expense or time, guess you can charge the customer again to the other one later

    • Why change when, clearly, there is nothing wrong with it. BTW, that is a YouTube video and not affiliated with this site at all except it was relevant to the content but I agree with the video. Besides the cost of copper is outrageous and the HVAC tech likely asked the homeowner what they wanted………….and the homeowner likely agreed that if there is nothing wrong with the other line then don’t replace it. So it is not always an HVAC technician trying to screw someone out of a few bucks as happens a lot in HVAC and most mechanical repair occupations.

  2. A question – Will the heat function work if the Freon has leaked out? For instance, if you don’t know there is a leak, and you haven’t used the a/c for a few days, and then you need to turn on the heat, will that part of the system work?

    • Almost all air source heat pumps (when you have a condensing unit outside) aside from a geothermal heat pump have some kind of back up heat such as the most popular, electric heat inside the air handler or as in the case of dual fuel heat pumps gas heat where the air handler is actually a gas furnace that provides the back up heat when the temperature outside gets too cold for the heat pump system to produce heat from the outside air.

      If you have a refrigerant leak then the obviously the heat pump will not work or work at a reduced efficiency rating depending on how much has leaked out. In that case when the house gets colder than the set point (~3 degrees F. below the set point depending on the thermostat) then the auxiliary or back up heat will kick in and provide heat so you should always have heat with a heat pump unless you have some sort of catastrophic failure with the system that prevents it from providing heat at all. The problem is that most back up heat sources whether it be gas or electric heat strips cost far more to run than using the process of refrigeration to provide heat. In other words, the system should only use the back up heat when necessary as it is set up to run. Get the leak fixed and return it to normal operation otherwise it is going to be an expensive heating season for you using only the back up heat source.

      Finally, most thermostats for heat pumps (not all) have a switch on the thermostat for auxiliary heat or emergency heat. That switch, when in the on position, utilizes the heat pumps back up heat so make sure if you want the heat pump to run normally that that switch is in the off position. If there is a problem with the condenser such as the one you are describing then by all means turn that switch (if your thermostat has that switch) to on position so you can have heat. If your thermostat does not have that switch then simply turn the set point up by 3 degrees F. above your comfort setting of the thermostat set point. Additionally, I do not know how you would know the heat pump has a leak unless it has a history of leaking in which case you really need to get the leak repaired. As the article mentioned, a lot of heat pumps get leaks in the accumulators so that would be a great place to check first. The technician should know where it is and what it is. The only other way you could know it had a refrigerant is if you had the skill to check the charge yourself which beyond most peoples ability unless you have been trained in it. A quick service call by a trained and skilled technician should identify any problems with the heat pump. Good Luck!!

  3. Hello!

    My heat pump outside ran out of Freon, seems like a large leak. The HVAC tech that came out used a probe to test for Freon and found that all around the bottom of the compressor (Black cylinder in the middle), was detecting leaked Freon (He put some in to pressurize the system). He quoted a new replacement system. When asked, he said a replacement compressor would be $2.500. It’s a Rheem 13PJA, 5ton we had replace in May ’09. It’s an r22 system (The blower inside is working, but around ’97). I love to replace it all with the new Puron system, but will have to wait to do that financially. If I could reasonably expect a replacement compressor to last a few years, that would be more than enough time to save for replacement of inside and outside systems.

    Thanks for the advice!

    • Sorry I am late responding to you………..get a second opinion especially when the technician recommends replacing the system. As #2 in the article states heat pumps can get large leaks in the accumulators and this can be easily repaired by replacing the accumulator. If the compressor is actually shot then yes replace the system but before you make that decision get a second opinion on the compressor.

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