Thermo King Precedent S-750i Trailer Refrigeration Unit
The Thermo King Precedent S-750i is the top of the Precedent range and the most technically advanced unit in the Precedent range. It introduced three things no previous trailer unit had: a three-speed engine, a next-generation control system, and a diesel-electric architecture in which the engine drives a generator rather than driving the compressor and fans directly. Listed at $38,500.
Precedent S-750i Specifications
Type: single-temperature nose-mount trailer refrigeration unit, diesel-electric
Engine: S-Series diesel with three selectable speeds, no DPF
Emissions: meets current and proposed CARB Ultra-Low-Emission TRU requirements
Refrigerant: R-452A, lower global warming potential than R-404A
Shore power: integrated, no separate standby package required
Telematics: TracKing embedded, 24 months of service included
Control: next-generation Thermo King control platform
Condition: new and low-hour units
Price: $38,500
What the Three-Speed Engine Buys You
Conventional trailer units have two engine speeds: high for pull-down, low for hold. The gap between them is wasted — at part load the unit either works harder than it needs to or cycles more than it should. A third intermediate speed lets the S-750i match engine output to the actual heat load, which cuts pull-down and recovery time, reduces the hours the engine spends running at all, and stretches maintenance intervals because those hours accumulate more slowly.
Diesel-Electric and R-452A
The diesel-electric layout decouples compressor speed from engine speed, which is what makes the three-speed strategy useful in the first place, and it makes shore power a native capability rather than a bolt-on motor. R-452A replaces R-404A with a substantially lower GWP charge — relevant now for corporate emissions reporting, and likely to be relevant later as F-gas style phase-downs tighten.
Who Buys One
Fleets on a long replacement cycle who want a unit that will still be compliant and serviceable in ten years, operators with sustainability reporting obligations to their retail customers, and anyone running California lanes who has been burned by a compliance deadline. If the economics do not justify it, the Precedent S-700 delivers similar cooling capacity for a fraction of the price.
Freight and Warranty
Ships on a flatbed with forklift loading. Freight is quoted to your delivery ZIP code. Contact us for current stock, build dates and warranty position before you order.
