Automatic Controls
Refrigeration and air-conditioning systems consist of refrigeration equipment and an electrical control circuit. These components are interconnected to produce and control the required cooling. Wiring diagrams of some typical automatic cooling control circuits used in refrigeration and air-conditioning systems are illustrated in Figures 9-31 and 9-32.
A cooling control circuit can be divided into the following principal components:
1. Basic controller or thermostat
2. Limit control
3. Primary control
4. Power supply
The relationships and functions of these various control system components are illustrated in Figure 9-31. Detailed descriptions of these components are given in a number of different chapters, especially Chapters 4 and 6 in Volume 2. Refer to the index for additional information.
Note
The compressor and fan controls are subject to early failure in an oversized air-conditioning system because the air conditioner is forced to turn on and off frequently. The corrosion of wires and terminals is also a problem in many systems. Regularly check all electrical wiring and contacts for loose connections, corrosion, and damage.
System Troubleshooting
Table 9-6 lists the most common operating problems associated with the system as a whole. For each problem and symptom, a possible cause and remedy are suggested.
