My heater in my dodge caravan does not blow hot

Get the heater core flushed or repair the valve that opens the coolant to the heater core.

First of all make sure your anti-freeze is at specification level's as well as make sure With the engine cold start the vehicle remove the radiator cap and make sure you see the flow of anti-freeze while keeping your hands as well as your clothing away from moving parts feel both hoses going into your heater core if the one on top of hot one on the bottom is cold then you have a Clogged heater core in which case you will need to flush the system . a simple garden hose will do the trick simply remove Both hoses to the heater core with the hose at the bottom line apply the garden hose until liquid comes out at the top of the other hose will probably see a lot of gunk. Also ensure that the vacuum line to the round ball under the hood is connected and not dry rotted.this will cause a vacuum leak to not allow the switch to fully engage from cold to hot. I hope this helps you.

Check your thermostat. It sounds as if it is stuck open and needs to be replaced. When they stick open, the car will take longer to warm up and will not reach normal operating temperture for a very long period of time. Also you will not get heat due to the fact that the engine never gets hot enough to produce anything but warm air.