Skip to main content

True/false: air conditioner is closed loop

Short answer

True. An air conditioner with a thermostat is closed-loop because the room temperature is measured and compared to the setpoint, and the error controls the compressor. The output affects the control action, which is the defining feature of closed-loop control.

State whether the following statement is true or false and justify: An air conditioning system is an example of closed loop control system.

True. An air-conditioning system with a thermostat is a closed-loop control system, because the room temperature (output) is measured and compared with the set temperature, and the difference decides whether the compressor runs.

 set   +  e  +----------+  +----------+  +------+ temp
 ----->(Σ)-->|Thermostat|->|Compressor|->| Room |-+->
        ^ -  +----------+  +----------+  +------+ |
        |                                         |
        +--------[Temperature sensor]<------------+
  • Reference: set temperature, e.g. 24 °C.
  • Sensor: a thermistor in the indoor unit measures the room temperature.
  • Controller: compares the two and switches the compressor on/off, or varies its speed in an inverter AC.
  • Plant: the room; disturbances: sunlight, people, opening doors.

If the room becomes warmer than 24 °C, an error appears (room temperature above the set value) and cooling increases; when the set value is reached, the compressor slows or stops. The output itself affects the control action, which is the defining feature of a closed loop.

Note: an old cooler or fan that runs at a fixed setting without a thermostat would be open loop.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Control Systems chapter 1 questions →