Trane overflow switch shutdown: cooling stops and nothing looks broken

What Does Error Overflow switch trip Mean?

An overflow switch on a Trane air handler interrupts the cooling call when condensate rises past the level it watches. The outdoor unit stops, the thermostat still shows a call, and nothing inside the house looks wrong. That combination is the switch doing its job: it stops the system before water reaches the ceiling below. Applies to: Trane air handlers and indoor coils fitted with a condensate overflow switch, as described in Trane homeowner support Overflow switches are fitted in several positions, including the primary pan, the secondary pan, and in the drain line itself, and not every Trane installation has one. Which switch tripped and how it is wired depends on the installation rather than on the model, so the answer comes from the installer's arrangement as much as from Trane literature. Owner-safe checks: Confirm the thermostat is calling for cooling and that no breaker or fuse serving the indoor or outdoor unit has operated. | Look into any visible drain pan beneath the indoor unit and note whether it holds water or shows a waterline stain. | After the system has been asked to cool for a while, go and look at where the drain discharges outside and see whether anything came out. Qualified technician: Clearing a condensate drain line, testing an overflow switch, and correcting drain fall or trap arrangement are service tasks on this equipment. | Never bypass or unplug an overflow switch to restore cooling. It is the only thing standing between a blocked drain and water in the structure below.