Symptoms of Low Refrigerant in Air Conditioners

Air conditioners are relatively simple machines that regularly tackle the monumental task of removing heat and humidity from our living spaces.

The Heart

Various refrigerant types are used in different applications.
This steadfast function is relied upon for months at a time, and even year-round in many applications. As long as a few basic requirements are fulfilled, an air conditioner goes about its purpose in quiet servitude. However, concern is soon raised for an air conditioner that falters in its performance. Symptoms of low refrigerant vary by the amount of the deficiency and the type of air conditioner system. .

The heart of any air conditioner is the compressor. This pump sucks in refrigerant vapor and compresses it into a liquid. The oil-laden refrigerant cools and lubricates the compressor. It is protected from operating with low refrigerant levels by a switch that turns the compressor off when the refrigerant pressure falls below a set value. Once the compressor stops, the refrigerant quickly expands and pressure builds. The low pressure cut-off switch is placated, and the cycle starts again.

The Brains

The thermostat also shuts off the compressor, but only after the selected temperature is achieved. This normal cycling process closely resembles symptoms created by slight refrigerant shortages. Selected temperatures are nearly attained, and compressor run times may seem normal. This condition may be revealed by high heat loads. A compressor that cycles off before lowering the temperature sufficiently may be lacking a small portion of its refrigerant charge. This symptom may escape notice if heat loads are moderate.

Obvious Signs

Excessively low refrigerant levels result in distinctly short compressor running times. This symptom is readily apparent from an appreciable loss of cooling, accompanied by the noise created by the compressor. This action is clearly perceptible in automotive air conditioners. The air conditioner clutch clicks when it engages the compressor. The compressor quickly draws down refrigerant pressure, and the low pressure switch disengages the clutch. The loud clicking sounds are only seconds apart when the system charge is seriously low.

Fail Safe

Most air conditioners are designed to halt compressor operation when little or no refrigerant is in the system. Safeguards are in place to protect the compressor if the low pressure switch fails or is bypassed. The compressor gets exceedingly hot when forced to run without the cooling and lubricating afforded by proper amounts of refrigerant. The heat melts a conductive material, interrupting power to the compressor. This type of device does not reset and will prevent compressor operation until it is replaced.

About the Author

Chris Weis is a freelance writer with hands-on experience in accident investigation, emergency vehicle operation and maintenance. He began his writing career writing curriculum and lectures in automotive mechanics at New York Technical Institute. Weis has contributed to "Florida" magazine and written procedure and safety guidelines for transportation concerns.