Four Seasons 6421R A/C Compressor Kit

Four Seasons PAC-Kit w/ Reman Compressor 6421R

Four Seasons 6421R is an A/C compressor kit built for classic GM applications that use an A6 compressor and expansion valve setup. It is a fitment-focused solution for restoring cabin cooling performance on select Cadillac, Buick, Oldsmobile, and Pontiac models from 1968-1973.

The PAC-Kit w/ Reman Compressor line combines the remanufactured compressor with the related A/C service components called out in the application notes, making it a practical choice when servicing older HVAC systems that rely on metric-thread or switch-equipped compressor configurations.

Key Features

• Four Seasons A/C compressor kit for classic vehicle HVAC service
• Part number 6421R for application lookup and ordering
• Fits select 1968-1973 Cadillac, Buick, Oldsmobile, and Pontiac models
• Application notes reference A6 compressor, expansion valve, pulley, switch, and thread configuration details
• Useful for restoring A/C compressor operation on vintage GM platforms

Detailed Description

Four Seasons 6421R is intended for vehicles listed with A6 compressor-based air conditioning systems, including Pontiac GTO, LeMans, Grand Prix, Bonneville, Catalina, Tempest, Buick Skylark, Buick LeSabre, Cadillac Eldorado, and Oldsmobile Cutlass and Cutlass Supreme applications. Fitment varies by year and configuration, so the notes should be matched carefully to the original compressor style, pulley diameter, and thread type before ordering. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

What It Helps Address

• Weak or failed A/C compressor performance
• Noisy compressor operation in older HVAC systems
• Loss of cabin cooling from compressor wear
• Service needs on A6 compressor-equipped classic GM vehicles
• Fitment matching for metric-thread, switch, or pulley-specific applications

Installation Notes and Tips

• Verify the vehicle’s original compressor style and application notes before installation.
• Match pulley diameter, thread type, and switch requirements to the listed fitment.
• Inspect the expansion valve and filter drier during A/C service.
• Flush the system and confirm correct oil specification during compressor replacement.
• Confirm all HVAC components are clean and free of contamination before reassembly.

Quality Assurance

Four Seasons is a recognized aftermarket brand for climate control components, and the PAC-Kit w/ Reman Compressor line is built around application-specific fitment data for classic A/C service. Part number 6421R should be matched to the exact vehicle listing to ensure proper installation and system compatibility.