heater doesn't work well

2003 Dodge Grand Caravan. heater doesn't work well. The blower works fine, but it doesn't blow very warm. it sometimes blows cold and other times blows slightly warm. It used to work very well and if set to full hot it would really blow hot air. As I said, the blower works fine and the temp gauge of van seems to indicate the coolant temp is normal. So I didn't think this was thermostat issue.

Has the coolant system ever been flushed?

1) The heater control valve might plugged, or not opening proper.
2) Check coolant level when cold, a shortage in coolant might keep thermostat from working proper.
3) Heater core could be plugged.
4) I would consider a good flush, including a back flush of the heat core, thermostat, and fresh coolant.

2003 Dodge Grand Caravan. heater doesn't work well. The blower works fine, but it doesn't blow very warm. it sometimes blows cold and other times blows slightly warm. It used to work very well and if set to full hot it would really blow hot air. As I said, the blower works fine and the temp gauge of van seems to indicate the coolant temp is normal. So I didn't think this was thermostat issue.
same problem that i was having with my 2003 t/c.it turned out to be one of the heater hoses that run down to the rear of the van was leaking,it had a hole on it.mine was leaking righ underneath the passanger side.check the antifreeze level.if it needs itfill it up and turn the van on and look around underneath the van and under the hood for any leaks.good luck

Yeah, when my van recently crapped out the water pump and rad, the temp gauge always stayed in the original spot and it never over heated, but the coolant level was low and caused weak heat from the heatercore.

thanks guys. no, it hasn't been flushed. good idea. It likely has that garbage antifreeze that clumps up, right? My 00 grand prix had that it it was a mess. I backflushed it and changed it over to the old stuff-ethylene glycol. Is the environmentally safe stuff (propylene glycol I believe) any better these days? My brother in law works on cars (mostly body work but knowledgeable about all aspects of cars) told me that there are problems with it, but that was several years back.

I think the level is OK, but will check to be sure.