There are a number of ways that the airflow over an evaporator can become restricted. Anytime the evaporator coil sees reduced airflow across its face, there will be a reduced heat load on the coil. No airflow will cause a lot of the refrigerant in the coil to remain a liquid and not vaporize.

The defrost termination/fan delay control is a temperature-activated, single pole-double throw switch controlled with a remote sensing bulb. The control can be an adjustable type. One example of the installation of an adjustable defrost termination/fan delay control is on a walk-in freezer’s evaporator.

Compressor performance curves are available from the compressor manufacturer for each of their compressors. Compressor data comes in either graph or table type. This article will take a closer look at the table type data and concentrate on the current (amps) performance data.

One of the main components of any refrigeration or air conditioning system is the condenser. As its name implies, one of the main functions of the condenser is to condense the refrigerant sent to it from the compressor. However, the condenser also has other functions.

Many modern day scroll compressors incorporate a variety of internal safety controls that can actuate the internal line break motor protection. Some safety features that can be found in the air conditioning scroll less than seven tons are described here.

Compressor capacity control is desirable for optimum system performance when loads vary over a wide range. Compressor capacity control through modulation can reduce power consumption, produce better dehumidification control, and reduce compressor cycling along with smaller compressor starting currents.

This is the second of three columns covering the scroll compressor. This article covers the scroll compressor’s advantages and the modulating scroll compressor. The third article will cover digital capacity control for scroll compressors and scroll compressor protection.

This is the first in a series of three articles covering the scroll compressor. This first article covers the history of the scroll compressor along with the scroll compressor operation.

This is the final article in a series covering inefficient compressors, noncondensibles in the system, low and high condenser entering air temperatures, and different metering devices as they apply to troubleshooting air conditioning systems.

This is the third in a series of columns on systematic air conditioning troubleshooting and diagnostics. This column deals with liquid subcooling, liquid and suction line restrictions, overcharges, and undercharges.