Dorman 34257 A/C Compressor Bypass Pulley

Brand Dorman 34257
Belt Type Serpentine
Compressor Type 10PS
Installation Instructions Included Yes
Material Aluminum Bracket
Material Plastic Pulley
Mounting Bracket Included Yes
Mounting Hardware Included No
Number of Pulleys Included 1
Outside Diameter 4.6
Package Contents Bracket and Pulleys
Fits Toyota · 10 vehicles

Bypass pulley. Keeps the original drive belt in use when the A/C compressor is inoperable.

Aluminum bracket. Plastic pulley construction balances strength with smooth belt operation.

Bracket included. Comes with installation instructions for a simpler setup.

Cross-references Four Seasons 4218NK, Four Seasons 97306 and Four Seasons 98306 for the same application. See all 15.

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Dorman 34257 A/C Compressor Bypass Pulley

Dorman 34257 is an A/C compressor bypass pulley that lets the original serpentine drive belt stay in service while bypassing an inoperable compressor. It is a practical repair option for 2003-2009 Toyota 4Runner and 2007-2009 Toyota FJ Cruiser applications when the A/C compressor is no longer functioning.

Key Features

  • Bypasses a failed A/C compressor while retaining the OE drive belt path
  • Aluminum bracket with a plastic pulley for application-specific fitment
  • 4.6-inch outside diameter
  • For serpentine belt systems
  • Includes mounting bracket and pulley assembly
  • Installation instructions included
  • Configured for 10PS compressor applications

Product Details

This Dorman A/C compressor bypass pulley, part number 34257, is built for vehicles that need the compressor removed from the belt drive without changing the original belt routing. It provides a direct mechanical bypass solution for Toyota 4Runner and Toyota FJ Cruiser models listed in the fitment data, helping keep the accessory drive system operating after compressor failure. This part cross-references Four Seasons 4218NK for the same application.

Common Problems It Can Address

  • Seized A/C compressor that prevents the belt from turning normally
  • Broken compressor clutch or internal compressor failure
  • Noise from a failing compressor pulley assembly
  • Need to keep the serpentine belt in place after compressor removal
  • Loss of accessory drive operation caused by a locked compressor

Installation Notes

Verify compressor type and belt routing before installation. This bypass pulley is for serpentine belt systems and includes the bracket and pulley assembly, while mounting hardware is not included. Installation instructions are included to support correct placement on the vehicle. Confirm fitment for 2003-2009 Toyota 4Runner and 2007-2009 Toyota FJ Cruiser before ordering.

Quality Assurance

Dorman supplies application-specific replacement components engineered to match the needs of the listed vehicle platforms. Part number 34257 is built for the confirmed Toyota 4Runner and Toyota FJ Cruiser fitments shown above.

This part fits 10 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelLitersCylindersPositionNotes
2009Toyota4Runner4.0LV6N/A
2009ToyotaFJ Cruiser4.0LV6N/A
2008Toyota4Runner4.0LV6N/A
2008ToyotaFJ Cruiser4.0LV6N/A
2007Toyota4Runner4.0LV6N/A
2007ToyotaFJ Cruiser4.0LV6N/A
2006Toyota4Runner4.0LV6N/A
2005Toyota4Runner4.0LV6N/A
2004Toyota4Runner4.0LV6N/A
2003Toyota4Runner4.0LV6N/A
Directly replaces or cross-references 15 part numbers
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
Four Seasons — 4218NKFour Seasons — 97306Four Seasons — 98306Global Parts Distributors LLC — 4711413Global Parts Distributors LLC — 6512256SKP — SK34257UAC — CO10834CUAC — KT2007UAC — KT2007AUAC — KT2007BUAC — KT5814UAC — KT5814AUAC — KT5814BTSN2720TSR2720