Getting no heat on a 1998 navigator replaced heater core an still want blow out heat

If both heater hoses are hot, then coolant is coming and going into/out of the heater core. The only thing that would affect heat would be a blend door not operating correctly. You will have to check the proper door that controls hot/cold air.

First check your fluid in your radiator if its low your heater will not work. Check all your heater hoses and make sure they are not kinked.
Your heater core may be plugged That will stop the heat flowing as well. If it's the heater core it will have to come out and replaced most likely. Not sure if there is a heater valve on that car.

Check whether the heater core is clogged by feeling the two tubes at the firewall that lead to the heater core. If they are cool rather than hot when the car is at normal operating temperature, the heater core will have to be flushed out, or replaced.

If the two tubes at the firewall are hot, but the interior doesn't get heat, then a blend door problem may exist where it is at the wrong angle due to a faulty vacuum motor, or control for the vacuum motor.

Good luck on getting heat inside of your 1998 Cadillac Deville.

have you checked the heater tap as in when you turn to hot on the dash the tap opens and allows the heated water to pass thru you rheater core?

Check that the two hoses of the heater core at the firewall are getting hot. If both are not hot, then the heater core is plugged up. Try to flush in this case to free up sediment. If that doesn't work, maybe a new heater core is required, assuming that the blend door is operating correctly, and diverting hot air to the defrost or front vents.

Sounds like your heater core went out or is plugged, try doing a coolent flush on your system and if that dont work then youll propably have to replace the heater core. Hope this helps

LOOK FOR BLOWN WINDOW CIRCUIT BREAKER.YOU HAVE A SHORT IN WINDOW SWITCH OR BAD WINDOW ELECTRIC MOTOR.YOUR HEAT PROBLEM IS A STOPPED UP HEATER CORES.THE STOP LEAK STOP ITS HEAT.THE STOP LEAK HAS STOPPED OR PLUGGED YOUR HEATER CORE SO COOLANT CANT PASS THROUGH IT.YOU GOING HAVE TO FIX RADIATOR LEAK AND REPLACE HEATER CORE TO GET HEAT AGAIN.

Since your blower is working and it is a heat issue,thats where we'll start,First thing is have you checked the coolant level in the radiator when engine is cold,make sure it is filled to top,next verify you have coolant in reserve ,Start your van and get it up to normal operation temperature,If your heat gauge on the dash works correctly it should be 190 degrees,Now lift the hood and locate the two heater hoses going into the heater assembly at the fire wall,Both hoses should be hot to hold on to,if both are hot and no heat inside your problem will be the blend air door in heater assembly.
if neither hose is that hot you need to replace the thermostat in the engine to get it up to 195 degrees.
if one hose is hot and one is luke warm then the heater core is blocked and to blame. hope this helps you.

sounds like it might be low on coolant. Low coolant levels will stop the flow and circulation to the heater core, and also might be the cause of overheating

The hoses from your heater core should be very hot to the touch. Check the hoses going to the core from the water pump. It should be very hot. The return hose should also be very hot. Now check the hoses going to the core. If they are not the same temp, then your heater control valve is not working correctly or the vacuum is not working. At any rate, locate the vacuum line going to the heater valve. Remove the silver bar on the valve from the plastic plunger arm. You will have heat all the time now if it was only a vacuum problem. You can fix it later when it's warmer out. BTW a 200* thermostat will make your heater even hotter.