Description
PAI Industries 450542 aftermarket fan clutch (cooling fan) switch — the 1/2″-14 NPT temperature switch that engages the engine cooling fan at 195°F on Navistar DT408, DT466, DT530, and DT466E / DT530E HEUI engines, plus Mack chassis using the Cummins-pattern fan clutch. Direct replacement for Navistar 1685132C92 and Mack 993605.
Signs You Need a New Fan Clutch Switch
- Engine runs hot in stop-and-go traffic but the cooling fan never engages
- Fan locks on continuously regardless of coolant temperature (excessive fan noise, fuel-economy loss)
- Coolant gauge climbs while the dash fan-on telltale stays off
- Visible coolant weeping at the switch’s 1/2″-14 NPT boss
Specifications
| Manufacturer | PAI Industries |
|---|---|
| Part Number | 450542 |
| Part Type | Fan Clutch / Cooling Fan Temperature Switch |
| Switch Logic | Normally closed, opens at 195°F |
| Thread | 1/2″-14 NPT (with lockpatch) |
| Overall Length | 2.46 in |
| Hex Across Flats | 0.88 in |
| Body / Top | Brass body, gray molded plastic top |
| Hardware Included | (2) 8 screws with star washers |
| Engine Compatibility | Navistar DT408, DT466, DT530, DT466E HEUI, DT530E HEUI |
Cross References
This fan clutch switch replaces or is equivalent to the following part numbers:
- Navistar: 1685132C92, 1685132C91, 1685132, 1612064C1, 1612064
- Mack: 993605, 3912-993605, 4333-1685132C92, 4333-1612064C1
- PAI Industries: 450542
- Fortpro: F238883
Applications
This fan clutch switch fits the following engines:
- Navistar DT408
- Navistar DT466 / DT466E HEUI 7.6L
- Navistar DT530 / DT530E HEUI 8.7L
- Mack chassis using the Cummins-pattern Horton / Bendix fan clutch
Representative trucks include International 4300, 4400, 7300, 7400, 7600, and 8500 / 8600, plus Mack CH/CHU/CXU and RD/CV vocational chassis equipped with this switch.
Verify thread size (1/2″-14 NPT) and switch logic (normally closed) against your existing switch — some fan systems use a normally-open or 207°F variant. Confirm before installing.
