Blend doors mechanism is fooked.
Search Blend door on the forum for causes & fixes.
1=dash out, the other 2, is going in through the side with an ebay fix.
This fault is so common on Grand Cherokees even videos are shown on you tube how to conduct this repair. To get this repaired at your dealer with dash removal without this kit will cost approximatelly £800.00-£1,000.00.
If your Jeep Grand Cherokee heater only blows cold on one side all of a sudden, or seemed to just quit producing heat one day - you most likely
suffer from blend door failure.
Blend doors are small airway control doors that move into positions to blend hot and cold air to your liking based on where you have the temperature setting knobs positioned. These little plastic flap doors hide behind your glove box in your A/C system's housing, and move up and down to pass heat or cold air as you command.The material has caused them to be weak and brittle allowing them to fall apart thus only allowing cold air through the vents
http://shop.ebay.co.uk/?_from=R40&_trksid=p3984.m570.l1313&_nkw=grand+cherokee+blend+door&_sacat=See-All-Categories