F4
Voltas Split AC
Severity: ModerateWhat Does This Error Mean?
F4 on a Voltas AC means the outdoor discharge temperature thermistor has a fault. This sensor monitors the temperature of hot refrigerant leaving the compressor — critical for compressor protection. F4 triggers a shutdown to prevent compressor overheating from undetected high discharge temperatures.
Affected Models
- Voltas Inverter Split AC (all capacities)
- Voltas 3 Star Inverter
- Voltas 5 Star Inverter
- Voltas Adjustable Inverter
- Voltas SAC series
Common Causes
- Discharge thermistor failed — resistance outside specification
- Thermistor wire broken or corroded inside the outdoor unit
- Connector at the outdoor PCB loose or moisture-damaged
- Thermistor probe not correctly mounted on the discharge pipe
- Outdoor PCB fault misreading the discharge sensor signal
How to Fix It
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Switch off the AC at the remote and circuit breaker. Wait 5 minutes and restart.
If F4 clears and the AC operates normally, monitor over the next few hours. A persistent F4 confirms the sensor has failed.
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Check the outdoor unit has full ventilation clearance on all sides.
A blocked outdoor unit causes discharge temperature to rise abnormally, which can push a borderline thermistor into fault range.
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Call Voltas service (1800-209-2000) if F4 persists.
Quote model number and error code F4 when booking your service visit.
When to Call a Professional
F4 requires a Voltas authorised technician — do not open the outdoor unit. Voltas customer care: 1800-209-2000. The technician will test discharge thermistor resistance and inspect the outdoor PCB.
Frequently Asked Questions
Is Voltas F4 expensive to repair?
No — a discharge thermistor sensor is an inexpensive part (Rs 200–600). Total repair including the Voltas service visit and labour is typically Rs 1,000–2,500. Under warranty, it is free of charge.