4 common causes of HVAC refrigerant line leaks

Heating and air conditioning unit in back of a residence

Every equipment or appliance you use is made of various components that are crucial to its functioning. Even if one component is damaged or starts to have some problem, your appliance or equipment will not be able to perform the function for which it is made properly. Similarly, your HVAC system has numerous components, one of which is the refrigerant line. The refrigerant line is responsible for the circulation of the refrigerant, which ultimately absorbs and releases the heat and makes the air cool. But sometimes, the refrigerant line may become damaged and/or start leaking, affecting the functioning of your system. Here we will discuss some common causes of HVAC refrigerant line leaks in detail, to give you a proper understanding of the problem.

Purpose of HVAC refrigerant line

Refrigerant is one of the basic things necessary for an HVAC to function properly. It is a blend of chemicals that circulate within your air conditioner. The refrigerant changes from liquid to gas while circulating through your system and absorbs and releases heat during the process. The refrigerant lines provide a passageway to the refrigerant for circulation. The refrigerant lines are a combination of two copper lines that serve the purpose of connecting the condenser and evaporator coil. 

The larger line, also called the suction line, carries the cool gas and is insulated to prevent any condensation and also increase efficiency. The larger line is also known as the vapour line or the return line. The smaller line carries warm liquid and is uninsulated. This smaller line is mostly known as the liquid line. 

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Causes of refrigerant line leaks

A damaged or leaking refrigerant line can cause increased energy usage, higher bills, and inefficiency of your system. If not repaired immediately, it can cause permanent damage to your system. The leaking refrigerant line is responsible for the frequent loss of refrigerant, prompting repeated recharge and the refrigerant cost is spiking regularly.

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There can be various reasons for leaking refrigerant lines, but let us have a look at some common causes of HVAC refrigerant line leaks.

  1. Pinhole leaks:

    Formaldehyde is a common element found in home building products and it naturally forms ‘formic acid’. When the formaldehyde accumulates on the copper lines, it forms formic acid which slowly eats away the copper lines and creates pinhole leaks. This usually happens after using the HVAC system for a long time. Along with the copper lines, the formic acid formation also affects the components of the system. Manufacturers have started replacing the copper lines with aluminium as they are not prone to corrosion. 

  2. System vibration:

    The outside unit of the HVAC system is comprised of a compressor and condenser. The compressor has a powerful motor and fan unit housed inside a metal cabinet and the motor works all the time the system is on. While running the motor makes vibrations but if the system is installed properly, a vibration isolator is attached to the system. These vibration isolators absorb any excess movement and keep the vibrations from circulating through the system. But, in case the HVAC is not installed properly and there is no vibration isolator attached to the system, the motor can cause severe vibrations while working. These vibrations can weaken or even fracture the refrigerant lines. In some cases, the clamps on the copper refrigerant lines can become loose causing them to rub against the system’s strut. These regular rubbings form holes in the unit, causing the refrigerant lines to leak.
    Image credit: Wikimedia Commons

  3. Line set damage:

    There are chances that the copper refrigerant lines connecting the condenser and the evaporator coils are pierced or damaged causing it to leak. The causes of such damage can be lawn mowers, construction work, someone tripping over the line set, or penetration by nails and/or screws driven into the walls of the building if proper protective measures are not taken. 

  4. Corrosion:

    Some amount of formaldehyde is present in the indoor air of almost every home which, over some time, creates corrosion known as Formicary corrosion. Formicary corrosion is a result of formic acid generated naturally by formaldehyde. This corrosion can attack the refrigerant lines made of copper, eventually resulting in refrigerant leaks at several places throughout the HVAC system. Even in the case of the heat pumps, the accumulators that are made of steel begin to corrode or rust after being used for some years, causing refrigerant leaks. 
    Image credit: Wikimedia Commons

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The refrigerant lines start to leak either after prolonged use or due to a lack of proper prevention. The refrigerant leak is a serious and dangerous matter and should not be taken lightly. The biggest problem with the leaking refrigerant line is that you will need to recharge the refrigerant more frequently, and it is an expensive component. Also, if the issue of leaking refrigerant is not dealt with properly on time, it will result in high energy bills and increased repair or service charges. So, whenever you notice leakage from your HVAC system, contact an expert at the earliest as if left unattended, this leakage can cause permanent damage to your system. It is always better to stop the problems at their beginning to avoid any further damage and huge repair bills.

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  1. 1

    I have a 407C condenser unit and I need to replace the evaporator coil due to a leak, so can I use an R22 coil as a replacement, strands, and if so, do I need to use the orifice from the existing coil or do I need to install a new one.

  2. 2
  3. 3

    We had a Mitsubishi heat pump installed 2016. Now leaking.
    We were told that the now-bankrupt company which provided defective refrigerant tubes commonly used with Mitsubishi heat pumps. is bankrupt. We were told there was a recall. We were NEVER notified of a recall.
    Can anyone give me more information?
    Eg, name of company?
    Was there an actual recall?

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