why does my heater blow cold air when my engine is idleing? on 2004 Nissan Altima

when i let off the gas my heater starts blowing cold air no matter when where or how it always does it

by in Gadsden, AL on October 30, 2012
2 answers
ANSWER by , October 30, 2012
ck coolant level 1st the poss sluggish blend door. scan codes and try blend doors with a scanner to make sure doors are operating properly
ANSWER by , October 30, 2012
possible blocked heater core