Blue Star AC Error F1
Diagnostic Protocol & Repair Guide
Technician Note
Always isolate power before inspecting high-voltage components.
Blue Star Error F1
Outdoor Sensor Failure.
Your AC cannot detect the outside weather.
Component
Ambient Sensor
Risk
Bird/Rat Damage
Fix
Replace Sensor
The “Weather Watcher” Problem
The F1 Error typically refers to the Outdoor Ambient Sensor. This little black probe hangs near the condenser coil to measure the outside air temperature.
Why it matters: Inverter ACs adjust the compressor speed and outdoor fan speed based on how hot it is outside. If this sensor fails (reads -40°C or +90°C), the system gets confused and shuts down to prevent overheating or freezing.
1 Visual Checks (Outdoor Unit)
Physical Damage
Look at the back of the outdoor unit. The sensor wire is often exposed. Birds and rats love to peck or chew these wires, causing an Open Circuit.
Jack Corrosion
Open the top cover of the outdoor unit. Check the sensor plug on the PCB. Rainwater often causes green rust (corrosion) on the pins, breaking the signal.
Sun Damage
After years of sun exposure, the wire insulation can become brittle and crack, leading to short circuits when it rains.
Atlas Aircon Repair Protocol
How we fix the F1 Fault:
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01.
Resistance Measurement We unplug the sensor and check its Ohms. Blue Star outdoor sensors are typically **10kΩ or 5kΩ** at 25°C. A reading of “OL” (Infinity) confirms a cut wire.
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02.
Sensor Replacement We replace the faulty sensor with a genuine Blue Star outdoor sensor assembly. We ensure the new wire is routed safely away from sharp edges.
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03.
PCB Cleaning If the jack was corroded, we use Contact cleaner spray to remove the rust from the PCB pins before plugging in the new sensor.
Estimated Repair Cost (Atlas Aircon)