heat

I have the same problem with my 2003 1500 4x4 Quad Cab. I've had the thermostat replaced as well as the radiator (clogged fins). I had heat when the mechanic test drove it with me and not it just blows lukewarm air. Anyone reply to you?

if your've replaced the thermostat and it's still not working well then it's the heater core (side of vehicle) that needs to be addressed, chances are it's clogged .

sounds to me like a heater core had the same problem on my 01 Ram, other clues are the widsheild always foggy with a oilly film on it and oilly film in the vents on the floor

low water level can do it. A bad heater control valve can do it.A plugged up radiator can do it.Extreme lack of service history can do it.Or a hairline crack in the block.