1999 Chevy Suburban V8 Four Wheel Drive Automatic 136658 miles
my suburban runs at proper operating temp. Coolant level is correct, heater hoses are warm, heater box is hot when heat is on. But only warm cold air blows through the vents. The heater/ac control head was damaged and would not switch positions ive replaced that, still blows cold?
Try warming the Vehicle, then carefully feel the heater hoses, are they both hot? If one is cooler than the other, You need to flush the core, or a replacement job on the heater core. Also if the system has a heat control valve on the heater hose, make sure it is working!