So im stationed in el paso and well i havent had to use the heat in my truck for some time now. and well i turned it on this morning blew hot for a litle then turn cold WTF. never ever seen this before anyone have any ideas.

 

Did you check your coolant level? What is the temperature gauge doing?

 

Maybe thermostat is stuck open?

 

Could it be something with the blenddoor?

 

I'd second the blend door.

 

Check water level and then check blend door. You should hear it whirr if you sit silent and turn the thermostat ****

 

The coolant level is normal and temp gauge sits right on the top of the symbol just its weird that it will work for little and the start blowing cold

 

Sounds like a blend door issue.
Once the hinge breaks, the blend door might sit in the correct position until vehicle motion bumps it the other way. At some point it is going to randomly move, and it will be the wrong temperature.
You might want to feel both heater hoses to be sure. If one is hot and one isn't when the heat is turned on, that would indicate a blocked heater core.
If they are both hot, that would indicate the coolant is flowing through the heater core and the problem is with the blend door.
The next step I would take is to remove the blend door motor (behind the black plastic on the transmission hump, or under the console depending on model) and check the motor to see if it is moving at all when you spin the temperature dial. If the motor activates, you most likely have yourself a broken blend door hinge.
Mine was $23 in stock at O'Reilly. And I was able to cut in behind the glove box to remove & replace it. Otherwise, you are looking at $120 for the Heater Treater 2 piece door, or a whole lot more work removing the blend box to fit the stock door..

 

Concur with everything Sam I Am said. Had problem with blend door in one truck, and in another had problem with sludge in the heater core on another. For the blend door, I did the same repair Sam I Am discusses. Blend door replacement took me about an hour and a half, start to finish, once I received the door and watched the video on the web site.

Cheers,
Scott

 

"...and in another had problem with sludge in the heater core on another." From the Department of Redundancy Department.