WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
When the engine coolant temperature is below 140°F (60°C), the PCM turns off the EVAP canister purge valve which cuts vacuum to the EVAP canister.
Fig 1: Identifying Evaporative Emission (EVAP) Control System Terminal And Coil