Dorman 34258 A/C Compressor Bypass Pulley

A/C Compressor Bypass Pulley for GM Applications

Dorman 34258 is an A/C compressor bypass pulley that lets the original serpentine drive belt stay in service while the inoperable compressor is taken out of the belt path. It is a practical repair for vehicles where the A/C compressor has failed but the rest of the accessory drive still needs to operate.

Compatible With 2004-2005 Chevrolet Impala, 2004-2005 Chevrolet Monte Carlo, 2004-2008 Pontiac Grand Prix, 2005-2009 Buick Allure, and 2005-2009 Buick LaCrosse.

• Aluminum bracket with a plastic pulley for the bypass assembly
• Built for serpentine belt routing
• Includes the mounting bracket and pulleys
• Outside diameter measures 4.78 in.
• Configured for CVC compressor applications
• Dorman 34258 cross-references Continental 67283 for the same application

Detailed Product Overview

This A/C compressor bypass pulley is used when the compressor is no longer operational but the vehicle still needs a stable belt path for the alternator, power steering, and other driven accessories. By replacing the failed compressor’s belt routing with a bypass assembly, Dorman 34258 helps maintain serpentine belt operation on GM vehicles such as the Buick LaCrosse, Pontiac Grand Prix, and Chevrolet Impala. The bracket-and-pulley design is intended for direct replacement in applications that use a CVC compressor layout.

What This Part Helps Address

• Broken or seized A/C compressor that prevents normal belt routing
• Squealing or belt damage caused by a locked compressor pulley
• Loss of accessory drive function after compressor failure
• Need to keep the serpentine belt in service without replacing the compressor immediately
• Vehicle downtime while the A/C system is being repaired or removed from service

Installation Notes and Tips

Verify compressor type, belt routing, and pulley alignment before installation. This part is for serpentine belt systems and includes the bracket and pulleys, but mounting hardware is not included. No installation instructions are included, so compare the original routing and mounting points to the vehicle before final assembly. Confirm fitment for your specific Buick Allure, Buick LaCrosse, Chevrolet Impala, Chevrolet Monte Carlo, or Pontiac Grand Prix by matching the compressor style and model year.

Quality Assurance

Dorman 34258 is built as a replacement bypass pulley assembly for service use on confirmed applications. It is engineered to restore belt routing after A/C compressor failure while maintaining the original drive belt path on the listed vehicles.