Nissan Repair: Nissan Quest 2000 A/C + Heater Malfunctions, temperature guage, nissan quest

Question
   Hi, last summer I noticed that front vent blow air slightly warmer than normal even with the a/c at maximum while rear vents blow ice-cold air with the a/c on. The front vents still  blow in slightly warm air  while rear vents blow in air at normal temperature with the a/c switch to off.
   Now in winter with engine temperature guage at normal(i.e. in almost the middle) and the blower/heater at maximum the front vents blow in cold air unless the engine is above 1,500-2,000RPM-i.e. cold air when stopped at traffic lights!
   Can anyone help me as winters are really cold here in Canada. Thanks and all help would be greatly appreciated.
AS

Answer
Saqib,

You either have a bad controller or the blend door is stuck.  It is under the dash on the passenger side and if you move your control from hot to cold you can see the arm move the door.  But, you will have to take the glove box off to get access.