Fujitsu General Air Conditioner Error 42

⚡ Quick Answer: Error code 42 on your Fujitsu General Air Conditioner indicates a communication failure between the indoor and outdoor units. This issue can lead to a... ✅ DIY Fixable

What Does Error 42 Mean?

Error code 42 on your Fujitsu General Air Conditioner indicates a communication failure between the indoor and outdoor units. This issue can lead to a blinking display and may cause the unit to stop functioning or enter a fault mode. To address this, verify the error display method for your specific model and consult the official manual for accurate interpretation. Power cycling the unit may also help resolve the issue temporarily.

Common Symptoms:

  • Error code displayed on unit remote or unit display.
  • Air conditioner may stop operation or enter fault mode when code appears.

Possible Causes

  • Wiring harness issue
  • Faulty control board
  • Interference from external sources

How to Fix Error 42

DIY Fix Basic Verification and Documentation Check

  1. Check the exact error display method for your specific Fujitsu General model (remote display or LED lamp flash).
  2. Consult the model’s official manual or the Fujitsu General support site to interpret code 42 precisely.
  3. Power cycle the unit (turn off for at least 5 minutes then restart) to see whether the error persists.

Technician Only Professional Diagnostic and Service

  1. Access the unit’s diagnostic/service mode (using remote sequence if applicable) to review the full service code record.
  2. Check internal connections, control boards, and system sensors relevant to any event logged when code 42 occurred.
  3. Refer to factory service documentation (model specific) for error 42 meaning and repair instructions.

Parts needed: Control board or electronics (potential), Wiring/communication lines (potential)

🛑 When to Call a Pro:
  • If error remains after basic reset and documentation lookup.
  • If unit is unresponsive to input or shows repeated faults.

Next step

Choose the next step for 42

Confirm the diagnosis before ordering. An error code can identify the system involved, but it does not prove that a specific part has failed.

Check during diagnosis

Most relevant component to inspect

HVAC Control Board

Controls fan, compressor, sensor, and communication functions in the HVAC unit.

Typical part-only price
$90 - $320
DIY difficulty
Hard
Estimated time
45-120 mins
Where can I find the model number?

Check the rating label around the door, lid, frame, rear panel, or inside the appliance cabinet. Use the complete model number, including suffixes.

Find a part that fits my model

Verify the complete model and part number on the retailer's compatibility page before ordering.

Other parts options

Check related components first; use model search as a fallback.

Model number required

Model-compatible Air Conditioner parts

Enter the complete model number to browse compatible replacement parts. This is a model-based parts search, not a diagnosis that a specific component failed.

Find a part that fits my model

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Optional routine care

Maintenance supplies

These products support cleaning or routine upkeep. They are separate from the possible repair components above and are not claimed to fix this error code or symptom.

Maintenance supply

Air Conditioner Fin Cleaner

For routine cleaning of accessible coil fins when permitted by the manufacturer. Disconnect power and follow product and appliance instructions.

View maintenance supply
Maintenance supply

Model-Compatible Washable AC Filter

A reusable filter option only where the appliance supports one. Match the full model, dimensions, and filter specification.

Compatibility check required: use the complete appliance model and compare the existing filter, bag, or specification before ordering.

Find one that fits my model

Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases. Recommendations are based on routine-care relevance, not commission rate.

Technical Specifications

note The previous model-independent part specification was removed. Verify the full model number and diagnosis in the manufacturer's official parts catalog before ordering.
part_number None

Common Questions

What does 42 error mean on Fujitsu General Air Conditioner?

Error 42 signifies a communication failure between indoor and outdoor units.

Can I fix Fujitsu General Air Conditioner 42 error myself?

Yes, check the error display method and power cycle the unit; consult the manual for details.

How much does it cost to fix 42 error?

Repair costs vary widely based on diagnostics and needed parts.

When should I call a technician for 42?

Call a technician if the error persists after a reset or if the unit is unresponsive.

Data last verified: 2026-07-31

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