How do I fix the problem of no heat in my 1999 Durango 5.9l

Check for a clogged radiator. Also check for proper fan operation. Do not mess with the cap. That has nothing to do with overheating.

sounds like you need more antifreeze , make sure fluid is at proper line on overflow tank

When you fill the radiator, did you make sure the car heater was set to Full Hot? If not, there could be an airlock in the water system. This can give the symptoms you describe.

Have you "burped" the system to get all of the trapped air out?? If you have the 4.7 motor, it helps to slightly elevate the front of the Durango.

Then, leave radiator cap off and start engine. Watch coolant level and open the system vent which is right off of the upper hose connection.

When air ceases to come out of the vent, secure it and top off coolant.

It helps to run the engine rpms up to 2-2.5 k in short bursts to help get the air out.

Make sure to have both front and rear heater systems on full heat during this process.

Don

have you had the water pump checked to make sure it is working?

I have the same problem. I have air, just no heat! 1999 Dodge Durango 5.2 Liter 4X4. When on low setting for the dash, it tries to blow warm.

you got more water than coolant.water pump drive belt slipping radiator core blocked cylinder block core blocked. or grille restricted.a bad radiator pressure cap. if all is good you might have head gasket leak.

Need to check your radiator flow, and thermostat, start the engine cold, with radiator cap off, watch for the water in the radiator, when it starts to bubble over let it, keep water hose close, radiator should blow back till the thermostat opens, the water will go down, and add more water if needed, and put the cap back on,,,, if your thermostat is stick closed it will cause over heating......and you may have to have it replaced.

If you havent already, leave the radiator cap off of your radiator while you start the vehicle. Be sure the engine is cold, you could get hurt if not because the coolant will build up pressure. If the cap is off, no pressure will build. Wait a while for the vehicle to heat up, look in the opening, and see if the coolant is flowing. If so, could be a bad fan, or gummed up radiator......if NOT your turbine on your water pump could be bad, OR, by chance, the thermostat is not working.

Have you checked your rad fans? Rad flow? Rad condition? Possible water pump problem if those check out good.