Peterbilt 357/378 AC Driers & Compressors

Frequently Asked Questions About Peterbilt 357/378 AC Driers & Compressors

What does the AC drier do, and how do I know mine needs replacing?

The AC drier (also called a receiver drier) removes moisture and contaminants from the refrigerant circulating through your truck's air conditioning system. If your AC is blowing warm air, cycling inconsistently, or you notice reduced cooling performance after a recharge, the drier is often the culprit, especially if the system has been opened up for repairs or has sat unused for an extended period. A clogged or saturated drier can also cause the compressor to work harder, leading to premature failure.

Will this AC compressor fit my specific Peterbilt 357 or 378 model year?

Compressor and drier applications can vary based on engine type, model year, and whether your truck has factory or aftermarket AC components installed. We recommend checking your existing part numbers or VIN details against the product listing specifications before ordering. If you're unsure about compatibility, our parts team can help confirm the correct match for your specific truck configuration.

Do I need to have my AC system evacuated before installing a new drier or compressor?

Yes. Any time you replace an AC drier or compressor, the system must be properly evacuated and recovered by a certified technician before the old component is removed. Installing these parts requires handling refrigerant, which is regulated and should only be done by someone with the proper equipment and certification, such as EPA 609 certification in the US.

Should I replace the drier when I install a new compressor?

In most cases, yes. Many technicians recommend replacing the drier whenever the AC system is opened for a compressor swap, since the drier's desiccant material absorbs moisture and can become saturated during the process. Skipping this step can introduce contaminants back into a freshly repaired system and shorten the lifespan of your new compressor.

What's the difference between a new, remanufactured, and aftermarket compressor?

New compressors are built from all new components and typically carry the longest warranty. Remanufactured compressors are rebuilt from cores using new wear parts and are tested to meet OEM specifications, often at a lower price point. Aftermarket compressors are manufactured by third parties to fit OEM specs but aren't produced by Peterbilt or the original component maker. Each option can be a solid choice depending on your budget and how long you plan to keep the truck, so consider your priorities before choosing.