First of all, the air conditioner system does NOT "consume" Freon or refrigerant. The system is designed as a SEALED air-tight system and the air conditioner does NOT burn or use up refrigerant to make your house cool. The refrigerant or Freon (Freon is a registered trademark name of Dupont Corporation and is widely used to described the refrigerant in you air conditioner or vehicle air conditioner) 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. If the refrigerant starts to leak OUT of the system, the system will still manage to cool for a period of time. It actually cools too much. The outdoor evaporator coil begins to freeze up because the temperature of the coil drops below the dew point. This is humidity or moisture which passes through the air conditioning coil for cooling (the same can also happen on the indoor coils). The air conditioning system experiences a reduced amount of air flow because of
the coil icing up. You may notice ice on the lines which run to the outside condenser. If you see this, it is important to shut the system off immediately and call a HVAC service company. If the system is left running the indoor evaporator coil could turn into a block of ice and no air flow will come out of the vents.
The HVAC service technician will need to determine the cause of your leak, and there is generally a charge involved to do so (I paid $234). There is two methods employed in determining the leak – (1) electronic R-22 "sniffer" leak detection, and (2) 2-week Dye testing (the system is refilled/recharged with dye and refrigerant and a UV light is then used to identify where any dye may be leaking out of the lines/coils). Do-it-yourself homeowners have also had limited success in utilizing a soapy-water solution that is sprayed on the surface of the coils and/or pressure lines and watching for bubbles percolating up on any surface where a leak is occurring.
Here are the reasons why your air conditioner might have a Freon or refrigerant leak:
- A Schrader valve is leaking Freon and needs to be replaced. There is a tool which can be used to change this Schrader valve without having to recover the entire amount of refrigerant from the system. These Schrader valves look like the small air 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. These Schrader valves are necessary and sometimes the rubber seals deteriorate or the Schrader 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.
- A capillary tube is leaking on the inside evaporator coil or on the outside 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 causing a hole to develop and Freon or refrigerant to leak. These leaks can be difficult to find because disassembly 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 TXVs need to be replaced and do not contribute to leaking Freon from the system.
- If the air conditioning 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.
- The indoor or outdoor air conditioning or heat pump coil (rows of tubes with cooling-fins upon them) 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 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 may still be 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 and after a few years they begin to rust. These rust holes allow Freon or refrigerant to leak out of the system. 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.
- The line set which carries refrigerant to and 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. A line set which runs under a roof can even be pierced by a nail when the roof is serviced or replaced. The refrigerant may take up to a year to leak out before the air conditioner is no longer functional.
That covers the major types of refrigerant leaks which occur with air conditioner systems. Depending on the age of the air conditioner system and the type of refrigerant leak which occurs, certain factors may determine whether you decide to service OR replace the air conditioner. 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. Take your time and weigh it carefully.
Example costs I was quoted recently:
- $90 service call
- $64 per pound of R22 R-22 refrigerant (my system was quoted as an 8-pound system, so $512 to re-fill it)
- $236 electronic leak test
- $2,154 inside coil replacement (parts & labor)
- $3,520 full A/C system replacement (parts & labor) Trane XR13 R410A 3-Ton A/C System
- $5,283 full A/C & Gas Heat systems replacement (parts & labor) Trane XR13 R410A 3-Ton A/C System, XR80 Gas Upflow furnace