This paper reports the first measurements at low temperatures (44-137 K) of rate coefficients for collision induced spin-orbit transitions, using a swarm experiment consisting of a uniform 'supersonic flow coupled with pulsed laser photolysis and laser-induced fluorescence techniques. It has been stated that both excitation and relaxation rates have a positive temperature dependence. The excitation (respectively relaxation) rate constant is 0.15 x 10(-12) cm(3) s(-1) (respectively 1.63 x 10(-12)) at 53 K and 2.76 x 10(-12) cm(3) s(-1) (respectively 4.48 x 10(-12)) at 137 K. A theoretical modelization of the Al-Ar system has been developed in the 30-300 K range, that reproduces the temperature dependence.