Hi there -
well first thing is to check the coolant level ,,, the heater core is usaly the highest point of the cooling system , and if the cooling system is low , its the first thing to not get coolant , so make sure the coolant level is good ,
if the coolant level is good , then when the problem happens , a good test to do to determine if its a cooling system problem or a internal dash problem ,,, is to when the problem happens , open the hood with the engine running and put your hand on the two heater hoses to the heater core,,,, a normale system will have both hoses hot ,,, if one is hot and the other is cold, then there is a cooling system problem , like bad t-stat , or water pump , or contaminated cooling system ,, if both are hot , then the cooling system is ok , and you have an internal problem in the truck , like a bad blend door motor - etc ,, this would be a good place to start to pinpoint ware the problem may lie ,.
we can go back and forth on this page
thanks, XXXXX XXXXX that a try and get back to you. it will take some time. can i get back to you on this same page or should i start over?
this page will stay open for days ,,, so when you get around to checking the stuff, just log back in and we go on this same question and ask more info
You were right on the money. Checked the coolant level, it was low, the water pump had a small leak. Had the water pump replaced and the coolant drained and filled. The heater works just fine now.
Many thanks, Lydon
HAY THATS GREAT NEWS