Pontiac Repair: heater switch, pontiac montana, heater fan

Question
why my rear heater doesn't work when you turn it on? 2000 pontiac montana van.

Answer
which switch doesn't work? the front or the rear? If it doesn't from from the rear the front has to be on aux control for the rear control head to work if the fan doesn't work from either switch then you have to check for power back at the rear heater fan resistor to see if you are getting the spped signals from the control head(S) then check for power and ground at the rear motor if ther is no power at the rera motor you have to trace it back into the resistior.