Why Too Much Refrigerant Is Harmful to Your Air Conditioner

Too much refrigerant is harmful to air conditioners and heat pumps despite what some may believe.  When air conditioners aren’t cooling properly, many people call us guessing that there must be some problem with the refrigerant levels. That is sometimes true but not always.

Unfortunately, adding too much refrigerant does about as much or more harm than not having enough refrigerant. This is why it is so important to call a licensed air conditioning professional who knows how to properly handle the refrigerant and can properly assess and charge your system with the right amount of refrigerant.

Understanding How Your Air Conditioner Uses Refrigerant

Most of us know that refrigerant is the “secret sauce” that makes an air conditioner work so well. Naturally, we want more cooling when it is hot. But more refrigerant does not equal more cooling. And, you definitely don’t want to “top off” any refrigerant.  Here’s the science behind why this is so.

Your air conditioner consists of an indoor evaporator coil connected to an outdoor condensing unit with a compressor, a mechanical motor and vapor pump that keeps the refrigerant flowing. In most applications, a metering device (aka, expansion valve, cap tube, or piston) is located in the evaporator coil and measures temperature and pressure. The compressor starts the refrigerant circulating when your thermostat calls for more cooling. If you compare these parts to an automobile, the compressor functions as the engine to circulate the refrigerant and the metering device acts as the automatic transmission, prompting the phase change of the refrigerant.

Your air conditioner operates as a closed-loop system; the same amount of refrigerant cycles back and forth, changing phases from liquid to gas and repeatedly.

As the refrigerant flows through the metering device, it changes its pressure and starts a phase change, which starts an endothermic reaction. This reaction enables the refrigerant to absorb heat from the indoors, so it can be transported outdoors. This causes the pipe to feel cold. The cool gas then circulates outdoors to the compressor and cools the motor.  The compressor compresses the gas, which causes it to get really hot. Then, the hot gas is circulated through the outdoor condensing unit coil from top to bottom. As the fan pulls air through the coil, it cools the hot gas enough so it condenses back into a liquid, an exothermic reaction as it sheds the heat. After the refrigerant returns to a liquid, the metering device can call for a new cycle of cooling.

Is Refrigerant a Liquid or Gas?

Refrigerants cycle between a liquid and gas phase, so the answer is both depending on where in the refrigeration loop it is located. Refrigerants have a very low boiling point in comparison to water, a liquid we are all pretty familiar with. This low boiling point explains how refrigerants are able to absorb thermal energy (indoor heat) and efficiently transfer it.

When the refrigerant is collecting heat, it gets cold which is an endothermic reaction. Endo means inside, so heat travels into the refrigerant. When the refrigerant is shedding heat, it is an exothermic reaction. Exo means outside, so heat is moving outside of the refrigerant.

When your refrigerant is added to your air conditioner, it is called charging the system. Charging refers to your AC technician’s monitoring of both the temperature and pressure of the refrigerant, so your system gets the right amount of refrigerant. The goal is to charge your system to factory specifications, so you don’t have too much or too little. The factory gives technicians a working range of refrigerant temperatures and pressures.

Working With Refrigerant

When an air conditioner is overcharged and has too much refrigerant, it can cause a breakdown and permanently damage the compressor.  Adding or removing refrigerant from your air conditioner requires specialized training, tools, gauges and scale, recovery bottles, and a special license from the EPA. Because refrigerants in use today can be damaging to the environment and human health, special care, training and real-world experience are required to properly handle them. It is never appropriate to release refrigerant into the air for these reasons. This is why we do not recommend this type of repair as a do-it-yourself or handyman repair.

When we see air conditioners with an improper charge with too much refrigerant, it is often because a technician was either inexperienced or overzealous, tried to inflate the service call ticket, or did not take the proper care and wrongly assumed the issue would resolve on its own.

Symptoms Your Air Conditioner May Have Too Much Refrigerant

How can you identify if your air conditioner is overcharged and has too much refrigerant before it is too late? On very high-end variable speed HVAC systems, in particular, compressors are very delicate. Compression of liquid or “slugging” is the number one cause of a variable speed compressor failure.

Insider tip: It is very important to replace air filters regularly especially for high-end, variable-speed HVAC systems as it greatly affects the heat transfer in the refrigerant cycle. Dirty air filters reduce airflow which reduces the heat transfer. This can cause the compressor to start slugging liquid, which behaves a lot like an overcharged system. Air conditioners in this condition present symptoms the same way as an air conditioner with too much refrigerant.

We witnessed one variable-speed HVAC system that went through three compressors in five years because the system was not regularly maintained. Avoiding situations like this is why we recommend regular HVAC maintenance in the spring for every air conditioner.

The following are symptoms we see when air conditioners have too much refrigerant. Keep in mind that these symptoms can also indicate different problems or part failures. Part of expert air conditioning repair involves a fair amount of investigative work.

1. Squealing or Whining Noises

   You may hear high-pitched whining noises if your compressor is “slugging liquid.” The compressor is a vapor pump and designed to compress gas, not liquid. When a system has too much refrigerant, there’s a danger of liquid refrigerant circulating into the compressor. The compressor can still operate but a breakdown is inevitable. The longer the compressor runs in this condition, the more damage is done to the system. The mechanical parts inside the compressor are designed for gas, so they can be permanently damaged when they are slugging liquid instead. This causes the compressor to work much harder.  The liquid refrigerant inside the compressor washes out the bearings and destroys the motor. That’s why you can sometimes hear squealing noises with liquids squeezing through spaces designed for vapor.

2. Air Conditioner Shuts Off In the Middle of the Day

   Sometimes we hear of air conditioners that shut off during the heat of the day, then begin operating normally in the evening. This can indicate high pressure and an overcharged system. If this behavior starts becoming a trend for your system, an overcharged air conditioner may be to blame.

3. Extremely Hot Air

   If you are noticing that your air conditioner is blowing extremely hot air from the condensing unit, it could mean your system is struggling to transfer enough heat outdoors.

4. Inefficient Operation

   A compressor that is not working efficiently is one that will work much harder for less return. If unresolved, having the wrong amount of refrigerant will wear out parts at best and at worst, will destroy your compressor altogether. If you are watching your bills and notice you are paying a lot more for electricity and experiencing less comfort indoors, this could be the reason.

Having Refrigerant Issues? We Can Help!

If your air conditioner is not working properly in the Fort Bend County and West Houston, Texas area, contact Summer, Rob and Kenny at 281-495-7830 to set up a fast and friendly service call. We’ll get to work on finding a solution to get your air conditioner cooling again in no time.

We have written more about refrigerants if you’d like to learn more about refrigerants and your air conditioner. Refrigerant types used in air conditioners are changing more often in response to stricter climate regulations. This can affect your decision to repair or replace your air conditioning unit. For example, if you have an older system using R-22 or Freon, it is a type of refrigerant that is no longer manufactured, which can be an issue if you have a refrigerant problem.

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