[lurch115]

you'll laugh but i had the same issue in my 4x4 and once while i had the dash pad off i turned the key on and cranked the fan up all the way...ran it in every setting and when i hit "vent" i coughed out alarge "hair ball" (sound deading mat) and ever since then my heater works great....another thing you can try is taking your glove box out and looking ontop of the heater box. there should be a couple of cables going to some linkage....move the heater control from hot to cold and see that they are moving all the way....or look under the hood and make sure that you even have vacuum to the going to the heater controls. thats a pretty common problem