Description
Aftermarket fan override pressure switch for Peterbilt and Kenworth A/C systems, replacing 79PSL3-4, P27-1051, MEI/Air Source 1310, and Red Dot RD5-4625-0. Normally closed switch opens at 310 psi and closes at 240 psi for R134a refrigerant, with a 2-pin connector and female M10-1.25 mounting thread.
Signs You Need a New Fan Override Switch
- A/C system fails to maintain cabin temperature on hot days
- Engine fan does not engage during high-pressure A/C operation
- Intermittent fan cycling or A/C clutch dropout
- High-side refrigerant pressure climbing above normal range
- Switch corrosion, cracked housing, or damaged terminals
Specifications
| Manufacturer | Predator HD Parts |
|---|---|
| Part Number | Replaces 79PSL3-4 |
| Part Type | Fan Override Pressure Switch |
| Operation | Normally Closed (N.C.) |
| Open Pressure | 310 psi |
| Close Pressure | 240 psi |
| Refrigerant | R134a |
| Thread Size | Female M10-1.25 |
| Pin Count | 2 |
| Vehicle Compatibility | Kenworth and Peterbilt heavy-duty trucks |
Cross References
This part replaces or is equivalent to the following part numbers:
- PACCAR / Peterbilt: P27-1051, F27-1051, P27-61-42
- Kenworth: 79PSL3-4, 79PSL34
- MEI / Air Source: 1310, PTAC1310
- Red Dot: RD5-4625-0
- Bergstrom: 2217003, 1000335581
- Mytee Products: MT1916
- Also known as: 11-1409, 111409, 29-30619, 850-8423, 912-1109, 9121109, 650469BSM, 128191, 220211, 2601184, ZGG711086
Applications
This fan override switch fits the A/C systems on the following heavy-duty trucks:
- Kenworth T300, T400, T600, T700, T800, W900 (1990s–2010s)
- Peterbilt 377, 378, 379, 385, 387, 388, 389 conventional models (1990s–2010s)
Verify the existing switch thread size, pressure rating, and pin configuration before ordering to confirm fitment.
