Frequently Asked Questions About Kenworth W900B/W900L Heat & AC Parts

Will these AC and heater parts fit my specific year W900B or W900L?

Most of our heat and AC components are designed to fit Kenworth W900B models from 1984-1987 and W900L models from 1987-present. However, there can be variations based on whether you have a factory sleeper, day cab, or aftermarket modifications. Always check the product description for specific year ranges, and if you're unsure, contact us with your VIN number for exact fitment verification.

What's the difference between OEM and aftermarket AC compressors, and which should I choose?

OEM compressors typically use Sanden or Seltec units that match factory specifications exactly, ensuring proper belt alignment and mounting. Aftermarket options can offer similar performance at lower costs but may require adapter brackets or different belt configurations. For trucks with original AC systems, OEM replacements usually install easier. If you're upgrading an older system or doing a complete overhaul, quality aftermarket units can be a smart choice.

Do I need special tools or professional installation for heater cores and evaporators?

Heater core replacement typically requires basic hand tools and 2-4 hours of labor, involving dashboard removal in most W900B/L models. Evaporator replacement is more complex, requiring AC system evacuation and recharge, which needs specialized equipment and EPA certification. While experienced mechanics can handle heater cores, we recommend professional installation for any component requiring refrigerant handling.

Why are there different heater box styles, and how do I identify which one I have?

Kenworth used several heater box designs across W900B/L production years. Early models (pre-1990) often have rectangular boxes with side-mount blower motors, while newer models feature more compact units with bottom-mount motors. The easiest identification method is checking the number and position of mounting studs on your firewall, or looking for a part number tag on your existing heater box. Photo comparison with our product listings can also help.

What maintenance items should I replace when installing a new AC compressor?

When replacing an AC compressor, always install a new receiver-drier or accumulator, expansion valve or orifice tube, and flush the entire system to remove debris. Replace all O-rings with new ones specifically rated for your refrigerant type (R134a or R12). Skip these steps and you risk immediate failure of your new compressor. Most compressor warranties require proof of these supporting component replacements.