My 90 doesn't seem to have hot heat. I call it Luke warm heat, it defrosts the windsheild, but if it's in the real cold, or in the single digits it's freezing me out. Is it my heater core, or something else,, what about that cooler on the pass. side. It never runs hot even with the a/c going. I want some warm heat!! Any info would be great.

Thanks
Billy D

 

what does your water temp get too. maybe thermostat stuck open.

 

sound like you need to replace your thermostat. if you change it get one from cummins, they last longer and flow alot better.

 

mine is a 93 and it takes it forever to warm up in the cold finally blocked 1/2 the radiator off with a thin piece of wood paneling works great now except it has warmed up in the last week and had to remove it. something about the set up in older dodges with cummins not getting very hot when its cold

 

Check the engine coolant temperature to make sure that it's getting up to temp.

There is a vacuum-operated heater core shunt-off valve in the engine compartment; during one mode of operation or another it closes to keep most of the water out of the heater core. It's spring-loaded in the open position, but I've seen them get dirty and sticky on other vehicles.

The blend door controlled by the red-blue slider could cause the problem if it's stuck or the cable connecting the slider to the door broke or became disconnected.

Back-flush the heater core to get 20 years of crap out of it.