Description
Restore cabin cooling with the 2601392 thermostatic switch. This 12/24V adjustable-temperature switch enables operator control of A/C compressor cycling via a knob-style interface. The 36-inch capillary tube accommodates standard evaporator installations in heavy-duty trucks and commercial equipment. Turning the knob adjusts the cut-in temperature across a 33–45°F range with a 5°F clutch cycling band.
Signs You Need a New Thermostatic Switch
- A/C compressor fails to cycle or cycles erratically
- Evaporator ices up even at highest temperature setting
- Air conditioning not responding to operator knob adjustments
- A/C stuck in continuous run mode and cannot be modulated
Specifications
| Manufacturer | Red Dot |
|---|---|
| Part Number | RD4125-36 |
| Part Type | Rotary Variable Thermostatic Switch |
| Voltage | 12/24V (bi-voltage) |
| Capillary Tube Length | 36 inches |
| Adjustable Temperature Range | 33°F to 45°F |
| Clutch Cycle Range | 5°F band |
| Refrigerant Type | R12/R134a |
| Control Type | Knob (manual) |
Cross References
This part replaces or is equivalent to the following part numbers:
- Red Dot OEM: RD4125-36, RD-4125-36P, RD-5-4125-36P
- Freightliner: RNCA10-6581-00
- Mack: A22-15817A
- Also known as: 9533N178, MVA1-1048, 71R2250
Applications
This rotary thermostatic switch fits:
- Freightliner Century, Classic, Columbia, FLD120 (with knob control)
- Mack CH, CL, CM, CS Series
- International, Peterbilt, and other heavy-duty trucks
- Refrigerated and specialty vehicle A/C systems
Verify your capillary tube length and electrical system voltage (12V or 24V) before ordering to confirm fitment.
