97 dodge grand caravan 3.8l little heat and then goes away

air in the system .before doing all that .you should have put a dadiator flush in the expansion bottle .then run it for about 20 miles then drain it.you do this to clean out the radiator core of dirt and rust.and it cleans the heater core .then bleed the air out by turning your heater of full .run the engine till water starts to get hot .then refit the cap.

There are two possibilities, one is the thermostat. Many people remove them which spoils the whole heating / cooling system. Since you changed the thermostat, I would check the heater valve on the heater which allows the hot water to circulate through the heating system.
It may be necessary to remove the heater box and flush the heater core since you talk about a lot of rust, which could have clogged the heater core and / or the pipes leading to the heater.

Sounds like something with bad bearings. Check in the area of air conditioner compressor or power steering and yes water pump.even the belt tightener will do that.

sounds like the air blend door actuator motor is stuck on cold position.

Have you topped off and bled the air out of the cooling system? Start there. You need a new thermostat and its possible the water pump is failing as well. Your cooling system may need to be flushed. Its also possible that your radiator needs to be replaced. Whatever you do, be sure that you don't drive the van until you've figured out what's going on and have repaired it. These engines are prone to head and head gasket problems (which may also be your issue) but if you catch it early enough and don't overheat severely, you can avoid that too. If you give me some more history I can try to help narrow the problem and come up with a plan of attack. Please let me know how you make out! Thanks and good luck!

Hi, Sounds like you need a radiator flush. If the radiator is plugged up it can not cool the engine properly. Have it cleaned out and it should work fine. Good luck.

If it is the head gasket you should see coolant in the oil or oil in the coolant. New thermostats can be bad right out of the new box. You can test them by boiling water on the stove and putting it in an watch to see if it opens at the right temperature. Between 185.F - 205.F (average is 195.F)

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your heater control valve might be faulty also. have a good day !!

How are your fluid levels? Low coolant flow can cause this. Does the heat go out intermittenly? i.e. when your idle will it go cold and then when you drive away does it get warm again. Could be a few things but, easiest is to make sure your coolant is at proper levels. If that all good try replacing the thermostat.

just because the gauge seems normal doesnt mean the thermostat is good, its 5 years old,and may be opening to soon, i would start by having the t-stat replaced and while thats being done have the cooling system flushed including a flush off the heatercore. i ve worked on a couple of these vans with heating problems, most were low on coolant due to a slow waterpup leak, the others with half plugged heatercores, due to the lack of coolant flushes. hope this helps.