Air Conditioner
Walton
Updated Jul 23, 2026
Walton AC F1 Error — Outdoor Ambient Temperature Sensor Fault & Fix
F1
Walton · Air ConditionerF1 on a Walton AC means the outdoor ambient temperature sensor (T4 thermistor) has an open…
Quick answer
F1 on a Walton AC means the outdoor ambient temperature sensor (T4 thermistor) has an open or short circuit.
What F1 means
The outdoor ambient sensor tells the control board how hot it is outside, so it can adjust compressor speed and manage defrost cycles. When this sensor fails, the board cannot operate efficiently and displays F1.
How to fix it
- Power off at the breaker.
- Locate the sensor — usually near the condenser coil air intake on the outdoor unit.
- Reseat the connector on the outdoor PCB.
- Measure resistance — approximately 10 kOhm at 25°C. Replace if open or zero.
- Check for weather damage — outdoor sensors degrade from sun, rain, and heat over time.
What does the F1 code mean?
F1 indicates the outdoor ambient temperature sensor (T4) has an open or short circuit.
Common causes
- Failed outdoor thermistor (UV and weather degradation)
- Loose connector on the outdoor PCB
- Wire damage (rodent damage common in Bangladesh)
- Outdoor PCB fault (rare)
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How to fix the F1 error
Power off
Isolate at the breaker.
Locate the sensor
Near the condenser air intake.
Reseat connector
Check at the outdoor PCB.
Measure resistance
About 10 kOhm at 25 degrees C.
Replace if faulty
Use a weather-rated replacement.
Safety first: Isolate power before opening the outdoor unit's electrical compartment.
Part you may need: Outdoor ambient temperature sensor (NTC thermistor)
Outdoor sensors are exposed to weather. Replacement every 5-7 years is normal in Bangladesh's climate.
Frequently asked questions
Will the AC still work with F1?
It may run in a degraded mode but without proper temperature data, efficiency and defrost performance suffer.
Can I use any 10k sensor?
Use a genuine Walton part or a matched NTC thermistor to ensure the resistance curve matches.
✎ Written by
REZAUL Karim (Riad)
REZAUL Karim (Riad) is the founder of ErrFixHub and a hands-on electronics and home-appliance repair specialist with over 15 years of experience diagnosing and fixing air conditioners, washing machines, refrigerators, inverters and other household appliances. He built ErrFixHub to turn cryptic error codes into clear, step-by-step fixes anyone can follow — cross-checking every code against manufacturer documentation and real repair-bench experience.
