My 1999 Ram 1500 5.9 doesn't have heat, i can smell antifreeze but it not leaking inside the cab (from what i can tell) it is leaking (not bad just dripping basically) on the passenger side somewhere between the engine and tire (closer to the tire). If I sit in idle for long periods I get like a steam or smoke coming from the vents inside the cab, my window fogs up also. I am going to replace the belt because it squeals at startup and sounds like a cricket almost constantly. Is this the heater core and belt or more?

 

Windows fogging up is a clear indicator of a leaking heater core.

 

Rent a pressure tester and find leak….put your hand on passenger side carpet and feel for any wetness up to firewall

 

Also be aware that it could be coming out of the AC drain tube and not into the floor. My 98 Durango did that.

 

The heater core sits in a cavity within the HVAC box and won't necessarily leak into the cab. Mine was completely shot and had a nice puddle in there. If your heat is wimpy and windows fog up, time to get that dash apart!

 

You should generally still have heat with a leaking core.

I'd absolutely chase down the leak you see, but I doubt that's the reason for no heat. I'd suspect clogged core or blend door issues

edit: or thermostat stuck open! Just fixed that on a 2000

 

Being low on coolant will also compromise heater performance.

 

These copper cores don't last forever. I bet if we looked at all our individual cores today they would be more than disgusting. I couldn't believe how bad mine was at 19 years old. I did a big flush back in 17 and that helped a little but the heat was never great. Now I keep it at halfway warm or I'm air fried out of the cab.

 

I wish I had that problem. Just did my heater core. Still barely any good heat

 

Like mentioned above, could be a blend door issue also, and for anyone looking at replacing the core I highly recommend pulling the dash and heater box apart. I know its more involved but doing things right has a bigger reward. The last one I did the A/C evaporator was plugged up resulting in almost no air flow. Thanks Dodge for not giving us a cabin air filter....