2000 dodge caravan heater blowing cold air only car does not overheat

You say you can hear the climate control work, but the blend door for the heater may not be moving. If both heater hoses are hot, I would suspect the blend door.

Most likely the problem is a broken blend door inside the heater box or a broken adjuster cable going to the blend door, the blend door inside the heater box is responsible for heater output depending on your temp adjustment on your heater control panel, most likely the blend door is stuck in the cold position allowing cold air to come through the vents verses allowing the blower motor to blow warm air past the hot heater core to produce heat, check the temperature adjuster cable behind your heater controls and make sure its connected and not broken, lastly make sure the blend door isnt broken and operating freely.

Replace the Thermostat and check operation.
You may also have to check and replace the Engine Coolant Temperature Sensor located on the backside of the Thermostat Housing.
Let me know if this helped, or if you have additional information or questions. Feel free to contact me on FixYa.com!

Check your coolant reservoir under the hood. Your water/antifreeze mixture is probably low. If it is like many other Dodges the smart design of the coolant system on the van causes a low coolant condition to first starve the heater core of coolant before the level gets so low that you overheat and hurt your engine. Likely you will have to add coolant a few times before the system gets all the air out of the heater core and engine caused by letting it get low, so check a couple of times a day until the coolant level in the reservoir remains at the Max Fill line when checked a few different times. That will signal when the system has removed all the air from the coolant system.

this sounds normal in very cold conditions! The air is never hot when you first start the car in any car, until the engine warms up, then the heater air will also warm. You could check your anti-freeze level for the first thing. If you don't have enough anti-freeze, it won't run through your heater to give you the proper heat

Have you checked the coolant level? What you describe is exactly what happens if the coolant level is low. When stopped at idle, hot coolant is not circulating through the heater core, so no heat. As the engine increases in rpm's when you pull away from the light, the water pump is spinning quicker, and some coolant is making it to the heater core. So check the level, and if it is low, keep an eye on it to see if it drops again. That of course indicates a leak somewhere. Get it fixed, as overheating the engine leads to costly repairs and worse case a new engine. Let me know how you make out with this.

In this order check the following:
Antifreeze level
thermostat
blend door
blend door motor...accordianman

Sounds like the air "blend" door might be inoperable. This door opens and closes a specified amount to regulate the amount of either cooled or heated air, as requested by the climate control unit. If the door is continually in the position which is bypassing the heater core (cold setting), the air will not get warm regardless of the condition/operation of the heater core. I'd suggest having this component checked.

Be sure the system is full of coolant. what Engine is in it?

my 2000 dodge caravan heat sometime working sometime not working