Modern split systems are controlled by a board in the indoor unit, a temperature sensor on the coil and in the return air, and a remote that talks to them. When any of these misreads or fails, the system does not cool — and from the room it looks identical to a refrigeration fault.
The remote and the receiver
Flat batteries and a failed infrared receiver are the trivial end of this, but they account for a real share of call-outs. A remote that shows a display but produces no response at the unit is worth testing with a phone camera, which will show the infrared LED flashing if it is transmitting.
Sensors
A room or coil sensor that has drifted out of tolerance will report a temperature the system has not reached, so the unit either never starts or never stops. Coil sensors that read falsely warm are a common cause of a system that runs continuously without ever satisfying the set point.
Error codes
Most manufacturers flash a fault code on the indoor display or through the operation lights, and those codes are specific: they distinguish sensor faults from communication faults from compressor protection. Reading the code before opening anything is the fastest route to the actual problem, and it is the first thing we do on an inverter unit.
Inverter boards
On inverter systems the outdoor board drives the compressor at variable speed and is the expensive control component. It fails from voltage surges and from moisture ingress. Surge protection at the distribution board is cheap insurance on any inverter installation.
Brands we fit and service
The thermostat, remote & control board market splits into hardware built for South African conditions and lookalikes that fail at the first hard season. These are the manufacturers we trust on our installations:
- Samsung
- LG
- Midea
- Hisense
- Daikin inverter and fixed-speed systems
See our brand guides for how these manufacturers compare.
When the thermostat, remote & control board goes wrong
These are the failures we're called to most often — each with its symptoms, causes and our fix on the dedicated problems page:
- Remote does nothing and the unit will not respond — Pressing buttons produces no beep and no response at the indoor unit, though the remote display itself may still light u…
- Unit runs continuously and never reaches the set temperature — The aircon runs without stopping, the room does eventually get cold, but the unit never cycles off, or conversely it sto…
See every thermostat, remote & control board problem & fix →
Need this fixed or installed?
Our Aircon Repairs service covers thermostat, remote & control board work — from R650, quoted upfront and backed by our 12-month workmanship warranty.