Your problem may be the blend door motor that controls the air flow over the heater core or the evaporator core. The blend door motor is located under the center of the dash. It is an electrical motor that moves a door in the case to change air flow direction. They are know for going bad and causing no heat or no cool air.
Remove the lower panel under the center of the dash, unbolt the air bag module, and the blend door motor can be removed and inspected.
The metal tube that starts at the back of the passenger side cylinder head goes under the intake to the back of the water pump. Below is a diagram of how it connects to the back of the water pump.
If the water pump is not flowing coolant, your engine will eventually overheat. You may have a restriction in the tube to the heater core through the metal tube under the intake. The intake manifold will have to be removed to get to the tube to remove it and inspect it.
ok I will ck this out tomorrow night. get back with you later.
I'am back. I removed the water pump tonight. There are no finns on the pump. SO the pump is bad. this suv has 173,000 miles on it. this is something to look for. thanks for all the info. talk to you again.