Air Conditioner
Walton
Updated Jul 28, 2026
Walton AC F4 Error — Outdoor EEPROM Fault & Fix
F4
Walton · Air ConditionerF4 on a Walton AC means the outdoor unit EEPROM (memory chip) has a read/write error. The…
Quick answer
F4 on a Walton AC means the outdoor unit EEPROM (memory chip) has a read/write error. The PCB cannot load its configuration data.
What F4 means
The EEPROM is a small memory chip on the outdoor PCB that stores the unit's factory configuration — model parameters, sensor calibration tables, and operating limits. When the board cannot read this chip, it displays F4 and refuses to start.
F4 is often caused by a power surge or brownout — common during Bangladesh's monsoon season when lightning strikes and voltage spikes are frequent.
How to fix it
- Power cycle — turn the breaker off for 10-15 minutes, then restore. This clears temporary EEPROM glitches caused by voltage spikes.
- Check for surge damage — if your area had a recent lightning strike or power outage, inspect the outdoor PCB for visible burn marks or swollen capacitors.
- Install a surge protector — on the AC's dedicated circuit to prevent future EEPROM corruption.
- If F4 persists — the outdoor PCB needs replacement. Some technicians can reflash the EEPROM if the chip is intact but data is corrupt.
- Call Walton service — Inverna and ACC series have 5-year inverter PCB warranty. Check your eligibility before paying for replacement.
Prevention: A good-quality surge protector on the AC circuit costs 500-1500 BDT and can save you from a 15,000-30,000 BDT PCB replacement.
What does the F4 code mean?
F4 indicates the outdoor EEPROM (configuration memory chip) has a read/write error. The PCB cannot load its factory settings.
Common causes
- Power surge or lightning strike corrupting EEPROM data
- Brownout or sudden power cut during operation
- Faulty EEPROM chip on the outdoor PCB
- Outdoor PCB failure
- Age-related chip degradation
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How to fix the F4 error
Power cycle
Breaker off for 10-15 minutes, then restore. This clears temporary glitches.
Inspect the PCB
Look for burn marks or swollen capacitors (qualified personnel only).
Install a surge protector
Prevents future EEPROM corruption from voltage spikes.
Call Walton service
If F4 persists, the PCB may need replacement or reflashing.
Check warranty
Inverna/ACC series have 5-year inverter PCB warranty.
Safety first: PCB replacement involves mains wiring. This must be done by a qualified technician. Do not attempt to reflash the EEPROM yourself.
Part you may need: Outdoor PCB (main control board) / surge protector
Walton's 5-year inverter PCB warranty (Inverna/ACC series) may cover F4 if the unit is under warranty and the damage is not from external causes.
Frequently asked questions
Can a power surge cause F4?
Yes — voltage spikes can corrupt the EEPROM. This is common in Bangladesh during monsoon storms.
Is the outdoor PCB expensive?
It is one of the more costly parts (15,000-30,000 BDT depending on model). Check warranty before paying.
How do I prevent F4?
Install a surge protector on the AC circuit. It costs a fraction of a PCB replacement.
✎ 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.
