Does the Nest Thermostat work with UAE AC systems?

In majority of the cases, the Nest would NOT work out of the box with UAE based AC systems. Nest is designed to work with US air conditioning systems that are very different in nature than GCC or UAE 220V AC systems. The main two differences are that GCC AC systems are usually controlled by a printed circuit board (PCB) or control unit (typically located in the indoor fan unit) that takes inputs from the thermostat and sends commands to both outdoor and indoor fan motors. Majority of air conditioning systems in the US do not have a PCB and control of the AC is done directly by commands from the thermostat itself which is directly connected to the indoor fan motor and compressor or actuator motors in chilled water systems.

The other main difference is the voltage. Voltage at thermostat location in US air conditioners is 24VAC where in GCC this would either be 5-12V DC for units with outdoor compressor or 220V for chiller water systems.

Fitting a Nest thermostats in the GCC involves the installation of conversion parts to deal with 24VAC input and  output of the Nest as well as bypassing of the AC control unit so that the Nest is then connected directly to AC itself. Parts and labour are included in the Nest PRO installation service that HomeIQ provides.