  The Dark Energy Spectroscopic Instrument (DESI) is under construction to
measure the expansion history of the Universe using the Baryon Acoustic
Oscillation technique. The spectra of 35 million galaxies and quasars over
14000 sq deg will be measured during the life of the experiment. A new prime
focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber
optic positioners. The fibers in turn feed ten broad-band spectrographs. To
achieve this goal, it is crucial to guarantee that fiber positioners work
properly under the extremes of potential operating conditions, including the
full range of temperatures, high speed wind disturbance etc. Thermal testing
provides valuable insight into the functionality of the fiber positioners that
can be used to help mitigate poor performance at extreme temperatures and wind
disturbance test provide guidance to design of ventilation system. Here, we
describe the thermal and wind disturbance tests for DESI fiber positioners and
how the test results helped improve the robustness of the positioners.
