More likely your problem is the higher inductive load that your motor has over the fan you tested with. Solid-state relays based on triacs and SCRs are subject to turn on and turn off problems due to fact that their reactance causes the voltage and current to go out of phase with each other and because such devices can only be turned off when current crosses zero. Here is a link that discusses the subject and possible solutions called snubber components.
http://nuwaveproducts.com/blog/2012/01/19/lets-talk-about-thyristor-scr-triac-and-ssr-snubbers/
Lefty