OBD Guide
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C1779

Blower Switch Failure

C1779 is an OBD-II diagnostic trouble code meaning: Blower Switch Failure. Common causes: fan speed switch malfunction, open or short circuit in wiring harness. Estimated repair cost: $33–111.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–111 (est.)

Symptoms

  • The fan does not turn on or only works at one speed
  • Unable to adjust fan speed
  • HVAC system is unstable

Causes

  • Fan speed switch malfunction
  • Open or short circuit in wiring harness
  • Fan relay problems
  • HVAC control unit malfunction

How to Fix

  1. Check the fan speed switch for mechanical damage
  2. Check the integrity of the wiring harness and contacts
  3. Check fan relay operation
  4. Replace switch or relay if necessary
  5. Reset the error and check the system operation

Related codes

B3890B3891C1780

FAQ

What does the C1779 code mean?

C1779 is an OBD-II diagnostic trouble code that indicates: Blower Switch Failure

What causes a C1779 error code?

The most common causes of C1779 include: Fan speed switch malfunction; Open or short circuit in wiring harness; Fan relay problems; HVAC control unit malfunction.

How do I fix a C1779 diagnostic trouble code?

To fix C1779: Check the fan speed switch for mechanical damage. Check the integrity of the wiring harness and contacts. Check fan relay operation. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1779?

Limited driving only, diagnose soon

How much does it cost to fix C1779?

The estimated repair cost for C1779 is $33–111. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat