Course: HET 119 HVACR Electricity II

Unit 12 Outline

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Unit 12 Outline

1. Operation Controls
  - Thermostats
  - Solid-state Time Delay
  - Low Ambient Fan Controls
2. Limit and Safety Controls
  - High Limit Controls
  - Fan Limit Switches
  - Pressure Switches
  - Compressor Overloads
3. Sequence of Operation
  - Call from the thermostat
  - Time Delay Circuit
  - Energizing the Compressor Contactor
  - Condenser Fan Motor Operation
  - Satisfying of the thermostat
4. Troubleshooting Heating Controls
  - Knowing What Should be Happening at any time
  - Using the Volt/Ohm Meter to Troubleshoot
  - Eliminating unnecessary Information and Concentrating on the Task at Hand
  - Replacing the Correct Component
  - Servicing Controls

Summary

- Since refrigeration maintains product and not people, different controls are used to maintain the product at varies temperatures.
- Control Devices are the part of an electrical system to operate when, how, where, and what will be turned on, off, and by a variable signal.
- HVAC/R systems need to control the temperature, pressure, flow, humidity, and level for the comfort of humans; thereby, it will be necessary to know all possible sequence of operations of a HVAC/R system.
- Controls can be binary (off and on), analog (variable), or integral (variable and adjusting) controls to give the most efficient control of a HVAC/R system.

Review the vocabulary terms listed below and look up their definitions / descriptions before taking the Vocabulary Quiz.

Vocabulary

- Pressure Switches
- Liquid Solenoid
- Time Delay Control
- Contactor
- Compressor
- Condenser Fan Motor
- Condensing Unit
- Electronic Controls
- Electronic Thermo-expansion Valve