[rovernc44]

My 1998 4.6 has started to only blow hot air when it is driving down the road or if you sit and hold the revs above 1500 rpm, sometime it take 1800 rpm's. But when you are driving it is usually fine.

 

[RangeRoMo]

did you try checking your anti freeze level? if you have to fill it and it drains again then you know you have a bigger issue. i hope that helps!

 

[kmagnuss]

Yep...your coolant is low.

PS..you have a leak.