Blower motor- 2011 Kia Sedona

I have a 2011 Kia Sedona.  Sometimes when i turn on my heater- only the
back is blowing out heat, the front and middle section of the van isn't
blowing out anything.This happens for a few days and then it works and
then goes back out.  I have two heating dials- one that controls the back
and one dial that controls the front and middle sections (1, 2, 3, 4 speeds).  
My mechanic says blower motor.  He also said the pigtail is burnt which is
the result of the blower  motor problem.  Thermostat looks to be fine- and
when the blower does work i have heat.  Does this sound right?