Thermostat sensor

A thermostat sensor is the small temperature probe built into a split-system indoor unit, a wall-mounted controller, or a ducted return. It measures the air at one fixed spot and passes that reading to the control board. The board compares it with the setpoint you chose on the remote and decides whether the compressor should run.

The sensor matters because it drives the cooling cycle. When the room reads above the setpoint, the compressor runs and the unit pulls heat out of the air. Once the reading drops to the target, the board shuts the compressor off and the fan may keep running for a short time. The cycle then repeats as the room warms again. A sensor that reads warm or cold compared with the room will make the unit stop too early, run too long, or short-cycle, which means switching on and off in quick bursts.

Placement affects accuracy. A sensor sitting in direct sunlight, close to a window, or right above a heat-producing appliance can report a false reading, and the unit will respond to that reading rather than to the room as a whole. Dust on the sensor or a loose connector can cause the same problem. Some newer units also use a sensor in the remote, so the room reading comes from wherever you are sitting.

If a unit seems to cool poorly or cycles oddly, a technician will often check the sensor reading against a handheld thermometer as part of the diagnosis. Aircon repair providers in Yishun handle this kind of check, and you can find them through the aircon repair category in this directory.

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