AUX AC Error Codes and Troubleshooting

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AUX AC Error Codes and Troubleshooting

AUX AC Error Codes and Troubleshooting Guide

Is your AUX air conditioner showing an error code like E1, E4, F3, H6, or U4 and not cooling properly?

Don’t worry.

This fully rewritten and SEO-optimized AUX AC Error Codes and Troubleshooting Guide (2026 Edition) explains everything clearly:

  • Complete AUX AC error code list

  • Meaning of each fault code

  • Possible causes

  • Step-by-step troubleshooting

  • DIY or technician difficulty level

  • Estimated repair cost (India 2026)

  • Preventive maintenance checklist

AUX Group is a globally growing air conditioning brand known for affordable inverter split AC systems. Like most modern air conditioners, AUX units have built-in self-diagnostic systems. When a fault occurs, the AC displays an error code to protect the compressor, PCB, and refrigerant system from serious damage.

Understanding these error codes helps you fix minor issues quickly and avoid expensive breakdowns.

How to Check AUX AC Error Code

Before troubleshooting, confirm the exact error code.

Method 1: Indoor LED Display

Most AUX split AC models show the error code directly on the front display panel.

Method 2: Remote Diagnostic Mode

  1. Turn ON the AC.

  2. Press and hold the “Check” or diagnostic button.

  3. The error code will appear on the remote display.

  4. Write it down before turning off the system.

Method 3: Blinking LED Pattern

Some models use blinking lights to indicate errors. Refer to the user manual for pattern decoding.

Always record the code before resetting.

Complete List of Common AUX AC Error Codes

Below are the most commonly reported AUX split and inverter AC error codes.

 E1 – Indoor Temperature Sensor Fault

Meaning:
Room temperature thermistor malfunction.

Common Causes:

  • Loose sensor wiring

  • Thermistor failure

  • PCB reading issue

Step-by-Step Troubleshooting:

  1. Turn off main power supply.

  2. Wait 5–10 minutes.

  3. Restart the AC.

  4. If error returns, sensor testing required.

Difficulty Level:  Medium
Estimated Cost (India): ₹800 – ₹2000

E2 – Indoor Coil Sensor Error

Meaning:
Evaporator temperature sensor fault.

Causes:

  • Moisture damage

  • Sensor burnout

  • Wiring disconnection

Solution:

  • Reset AC.

  • Check cooling performance.

  • Replace faulty thermistor if needed.

Difficulty:  Medium to High
Cost: ₹1000 – ₹2500

 E3 – Indoor Fan Motor Fault

Meaning:
Fan motor speed abnormal.

Causes:

  • Dust blockage

  • Motor capacitor problem

  • Loose wiring

Step-by-Step Solution:

  1. Clean air filters.

  2. Ensure proper airflow.

  3. If fan stops or makes noise, technician inspection required.

Difficulty:  Medium
Cost: ₹3000 – ₹6000

 E4 – High Discharge Temperature Protection

Meaning:
Compressor overheating.

Causes:

  • Dirty condenser coil

  • Refrigerant imbalance

  • Poor ventilation

Solution:

  • Clean outdoor unit.

  • Ensure airflow clearance.

  • Technician should check refrigerant pressure.

Difficulty: Medium to High
Cost: ₹1500 – ₹4000

E5 – Overcurrent Protection

Meaning:
Compressor drawing excessive current.

Common Causes:

  • Voltage fluctuation

  • Compressor failure

  • PCB malfunction

What to Do:

  • Turn off AC immediately.

  • Avoid repeated restart attempts.

  • Contact authorized technician.

Difficulty: High
Cost: ₹5000 – ₹12000

F1 – Outdoor Temperature Sensor Fault

Meaning:
Outdoor thermistor malfunction.

Causes:

  • Environmental damage

  • Wiring fault

  • Sensor failure

Solution:
Professional testing and replacement required.

Difficulty: High
Cost: ₹1500 – ₹3000

F3 – Refrigerant Shortage (Low Gas Pressure)

Meaning:
Low refrigerant level detected.

Causes:

  • Gas leakage

  • Loose pipe joints

  • Installation error

Step-by-Step Solution:

  1. Turn off AC.

  2. Inspect copper pipe joints for oil stains.

  3. Perform professional leak test.

  4. Repair and refill refrigerant.

Difficulty: High
Cost: ₹2000 – ₹4500

H6 – Compressor Lock Protection

Meaning:
Compressor unable to start.

Causes:

  • Compressor seizure

  • Power surge

  • PCB fault

Solution:

  • Switch off main power.

  • Wait 10 minutes.

  • If issue continues, compressor inspection required.

Difficulty:  Very High
Cost: ₹9000+

 U4 – Indoor & Outdoor Communication Error

Meaning:
Communication failure between units.

Causes:

  • Damaged communication cable

  • Loose terminals

  • PCB issue

Solution:

  • Restart AC.

  • Technician should inspect wiring and PCB.

Difficulty: High
Cost: ₹3000 – ₹8000

Quick Reference Table – AUX AC Error Codes

Error Code Meaning Main Cause Difficulty
E1 Room sensor fault Thermistor issue Medium
E2 Coil sensor error Sensor damage Medium
E3 Fan motor issue Motor or wiring Medium
E4 High temp Dirty condenser Medium
E5 Overcurrent Compressor fault High
F3 Gas shortage Leakage High
H6 Compressor lock Motor issue Very High
U4 Communication Wiring/PCB High

Minor vs Major AUX AC Error Codes

Minor (DIY Possible)

  • E1

  • E3

  • E4

Often fixed by:

  • Cleaning filters

  • Resetting power

  • Clearing airflow blockage

 Major (Technician Required)

  • E5

  • F3

  • H6

  • U4

These involve compressor, refrigerant, or PCB repairs.

Estimated AUX AC Repair Cost in India (2026)

Issue Approx Cost
Sensor Replacement ₹800 – ₹2000
Gas Refill ₹2000 – ₹4500
Fan Motor Repair ₹3000 – ₹6000
PCB Replacement ₹5000 – ₹12000
Compressor Replacement ₹9000+

Costs vary depending on model and city.

Common Reasons Why AUX AC Shows Error Codes

  1.  Poor maintenance
  2.  Voltage fluctuation
  3.  Refrigerant leakage
  4.  Dust accumulation
  5.  Water leakage
  6.  Aging components

Regular servicing reduces breakdown risk significantly.

Preventive Maintenance Tips for AUX AC

  •  Clean air filters every 30 days
  •  Service AC before peak summer
  • Install voltage stabilizer
  • Keep outdoor unit clean
  • Check drain pipe regularly
  • Ensure professional installation

Preventive care reduces up to 70% of major issues.

When Should You Call a Technician Immediately?

Call service support if:

  • Compressor-related error appears

  • AC trips MCB frequently

  • Burning smell detected

  • Loud abnormal noise

  • Refrigerant leakage suspected

Never attempt PCB or compressor repair yourself.

Is AUX AC Reliable?

AUX Group air conditioners are known for:

  • Affordable pricing
  • Decent inverter technology
  •  Competitive cooling performance

They are ideal for budget-conscious buyers but require proper maintenance for long lifespan.

Frequently Asked Questions (FAQ)

How do I reset my AUX AC?

Turn off the main power supply for 5–10 minutes and restart.

What does F3 mean in AUX AC?

F3 indicates refrigerant shortage or gas leakage.

Why is my AUX AC showing E5?

E5 means overcurrent protection due to compressor or voltage issue.

Can I fix AUX AC sensor errors myself?

You can try resetting, but sensor replacement requires technician tools.

Is refrigerant refill covered under warranty?

Usually not unless it’s a manufacturing defect.

Final Summary

AUX AC error codes are protective diagnostic alerts designed to safeguard:

  • Compressor

  • Sensors

  • Fan motor

  • PCB

  • Refrigerant system

Understanding each error code helps you:

  •  Avoid panic
  • Save repair cost
  • Prevent major breakdown
  • Extend AC lifespan

Minor issues → Clean and reset.
Major issues → Call professional immediately.

Conclusion

AUX AC error codes are intelligent safety features built into modern inverter systems.

Whether it’s E1 sensor fault, F3 refrigerant shortage, or H6 compressor lock, identifying the problem early can save thousands in repair costs.

Regular maintenance, voltage protection, and proper installation ensure your AUX air conditioner operates efficiently for years.

If the error persists after reset, always contact authorized service for safe and reliable repair.

Stay informed. Stay cool.

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