Frequently Asked Questions About Peterbilt 330/335/337 AC Driers & Compressors

Which AC drier fits my specific Peterbilt 330, 335, or 337 model year?

AC driers for Peterbilt 330/335/337 models typically fit trucks manufactured from 2005-2015, but exact compatibility depends on your engine configuration and AC system type. Models with Caterpillar C7 engines often use different driers than those with Cummins ISB or ISC engines. Check your existing drier's part number (usually stamped on the canister) or verify fitment using your VIN before ordering. Most universal driers with 3/8" male O-ring fittings will work, but OEM-spec units ensure proper refrigerant flow rates.

How difficult is it to replace the AC compressor on these medium-duty Peterbilts?

Replacing an AC compressor on a Peterbilt 330/335/337 typically takes 2-4 hours for experienced technicians. The main challenges include limited access space between the engine and firewall, especially on models with automatic transmissions. You'll need to evacuate the AC system, remove the serpentine belt, disconnect refrigerant lines, and unbolt the compressor from its bracket. Most installations require basic hand tools plus AC-specific equipment like a vacuum pump and refrigerant recovery machine. Professional installation is recommended if you lack AC service equipment.

What are the signs my AC drier needs replacement versus just the compressor?

Replace your AC drier whenever you replace the compressor or open the AC system for major repairs. Common signs of a failing drier include intermittent cooling, excessive moisture at the sight glass, or metallic debris in the system (indicating compressor failure). If your compressor failed due to liquid slugging or bearing damage, the drier is likely contaminated and must be replaced to prevent damaging the new compressor. A clogged drier will cause high pressure readings on the low side and poor cooling performance.

Do aftermarket AC compressors last as long as OEM units for these trucks?

Quality aftermarket compressors from reputable manufacturers like Sanden, Denso, or Four Seasons typically last 5-7 years with proper maintenance, compared to 7-10 years for OEM units. The key difference is often the clutch assembly quality and internal tolerances. Aftermarket units work well for most applications but may cycle more frequently or produce slightly more noise. For maximum longevity, choose new over remanufactured compressors and always replace the drier, orifice tube, and O-rings during installation.

What's the correct refrigerant capacity and oil type for these AC systems?

Peterbilt 330/335/337 models use R-134a refrigerant with typical system capacities ranging from 2.5 to 3.2 pounds, depending on cab configuration and optional rear AC. Standard systems require PAG 46 oil (6-8 ounces total system capacity), while some newer models may use PAG 100. Never mix oil types or use universal oils, as this can damage seals and reduce compressor life. Check the underhood AC specification label for your exact capacity, as dual evaporator systems require additional refrigerant.