about a year fter i bought my 04 impala, the heat stopped working on the drivers side, and it was winter, so i drove all winter with no heat, and then a year later it jsut started to work again, once again it was winter, but now it has stopped again..... PLEASE someone help me!!!!

 

to clarify; you have airflow from the blower motor but only cold air?
if thats the case; start by checking the coolant level.

if thats ok, check for movement of the temperature blend door when you move from full hot to full cold position.

also...how is the fuel mileage? bad = thermostat stuck open..will set a dtc.

 

You said that the heat stopped working on the drivers side. Does that mean it was working on the passenger side? If so you need to look at the blend door actuator.