a friend of mine has a 1996 grand cherokee he just replaced the heater core and thermostat and still has no heat said the core warms up but only blows cold air through the vents any ideas or suggestions, was told possibly they left something unhooked when they switched out the heater cores

 

they could have left a vacuum line off that controlled the flow of coolant. or one of the ones inside the dash that opens the door.

 

The temp cable get hooked back up? On a cherokee it's under the dash on the passenger side. I dont know about where they put it on the Grand Cherokee, but I would think it would be around the same location. That s my guess.
Good luck.