Help keep your truck's A/C system working within safe pressure limits with the Four Seasons switch 35889, a system-mounted trinary pressure switch that monitors refrigerant pressure and combines three switch functions in one unit. It fits many commercial trucks, among them the 1988-1992 Peterbilt 376, 1989-1997 Kenworth T400 and 1988-1990 Kenworth C540. See the Buyer's Guide tab for the full list.
A trinary switch typically provides low-pressure and high-pressure cutouts that help protect the compressor. Its third switch point is commonly used for cooling-fan control. Four Seasons engineers and tests the 35889 and builds it for specific vehicle applications, backed by more than 50 years of mobile A/C experience.
- Corrosion protection: The switch is zinc-coated to resist corrosion.
- Vehicle-specific design: It is a direct-fit replacement for the listed applications.
- Sealing components: It comes packaged with the gaskets, O-rings or seals intended for a proper replacement.
- Easy identification: The switch is color coded so you can identify it quickly.
Signs this part may need replacing: The compressor won't engage or cycles erratically, the vents blow warm air, or the cooling fan doesn't respond as expected with the A/C on. These signs can have other causes, so diagnose the system before you replace parts. If a failed pressure switch is the cause, the 35889 replaces it. For installation, consult the vehicle service information and follow proper A/C service procedures.
