On my 2002 Caravan I had a to repair the rear heater lines.

Since doing that I don't have any heat.

Have purged the system,replaced the thermostat and checked the cores for blockage had none.

When you drive it the temp gauge will run in the middle for a while and then it will go to the hot side(the light comes on) the shortly after it will come down to the middle mark.

Really weird.

Could it possibly be the water pump?

I have drove it,let cool down and toped off the radiator 3 or 4 times.

The upper rad hose and core inlet hose gets hot.

Doesn't seen to circulate.

Any help is appreciated.

Tim..

 

If you can, see if the heater core feels hot. If not then you may have air in the system.. or a dying water pump.

 

Sure sounds like the water pump is not circulating the coolant; probably a broken or slipping impeller. I like the GMB new water pumps.

 

Check belts and thermostat while you're at it. I think your pump has gone south as well.