The fan blades might be obstructed by debris (e.g., leaves, plastic, or a bird's nest) causing the motor to jam and trip its fuse/overload protection. Alternatively, if the fan bearings seized or the fan is physically stuck, the motor will quickly overload on startup.
Over time, fan motors can wear and begin drawing higher amperage due to internal faults (bad windings, etc.). This can cause overload trips even without an external blockage.
A phase loss or voltage drop to that motor could make it draw more current. If one leg of a three-phase fan motor lost power (blown fuse or bad contactor), the motor may stall and overload. Similarly, a failed start capacitor on a single-phase fan motor can prevent it from turning, leading to an overload condition.
In rare cases, if the fan is undersized for a very hot day, it might run constantly at max effort and potentially overheat. But fans are usually rated for continuous duty, so look to mechanical/electrical causes first.
Turn off the chiller to ensure the fan won't suddenly start. Physically inspect Fan 1's blades and area for any foreign objects. Remove any debris or obstructions manually. Try spinning the fan blade by hand (power off!) to feel if it moves freely or if it's binding.
Open the chiller's electrical panel (only if trained to do so). Locate the overload for Fan 1 (often labeled corresponding to the fan motor, could be something like Q4 or similar). Press the reset on that overload protector to re-enable the fan circuit.
While in the panel, look at the fan motor's contactor and wiring. Any signs of burnt contacts or loose wires should be addressed (if you're qualified). Also, if the fan motor has a capacitor (for single-phase units), inspect it for bulging or damage; a bad capacitor can cause hard starting.
Turn the chiller on and observe Fan 1 when it's commanded to run. It should start up smoothly. Verify that the fan is spinning properly and blowing air through the condenser.
Let the chiller run and see if Fan 1 stays on without tripping again. Check the motor amperage if possible or at least monitor the sound and speed of the fan. It should run continuously (or cycle normally with load) without issue. Also note if the earlier high-pressure condition subsides now that the fan is back online.
They can perform tests on the motor windings and replace the motor if necessary. A technician can evaluate whether all fans are operating at full capacity, and if the condenser coil is clean and airflow is sufficient. In some cases, they might recommend upgrading fan motors or adding fan cycling controls for very hot weather operation.
