How does the system behave from minus 20 degrees cold to plus 85 degrees heat?
The HCT400 and HCT402 electronics are specified to operate between −20 and +85 degrees. Within that range, however, the limiting factor is usually not the electronics but the hydraulic side: with cold, viscous oil the lever response slows, while with very hot oil the viscosity drops and internal leakage increases. The remote's internal battery also drains faster in extreme cold.
Temperature affects three separate layers differently.
Electronics: the specified operating range of both models is −20 / +85 degrees. The motor housing is IP67 rated; against condensation risk it is important that connectors are fully seated.
Hydraulic oil: cold oil is viscous, passes through the pump and valve with more difficulty, and the delay between lever movement and cylinder response grows. The correct practice is to warm the system up unloaded before starting work. At high temperature, as viscosity drops, internal leakage increases, movement gets "softer" and precision decreases.
Battery: chemical capacity drops at low temperature; the remote's charge drains faster in the cold. The HCT402 does not allow motion control at critical level, which makes the start-of-shift charge check even more important on cold sites.
The interior of a cab parked in the sun can approach the upper limit in summer. Storing the remote in the shade or in the cab rather than leaving it in the sun is better for both battery and electronics life.
Full coverage of this topic: What Is a Hydraulic Lever Retrofit Kit? Definition, Components, Operating Principle