2002 Dodge Caravan strange heater problem?

[marc]

My heater will not blow warm air until the engine temperature comes up to a certain temp. The engine seems to heat up normally, looking at the gauge. Until recently, I could feel the heater air warming up along with the engine temp. But now no warm air blows in until the temp gauge is showing just about 1/2. Gotta love these non-specific gauges

Usually, once it hits 1/2 and the heat comes on, it's fine. And I can regulate fine, too. When full on, I get all the heat I expect.

This isn't a horrible situation, as it does eventually turn on. But if I get on the highway soon, before it gets to 1/2, highway speeds tend to keep it cool enough to not allow it to turn on. And when winter shows up soon, I may never get heat.

Thanks for any ideas.

[MrK]

any problem with coolant circulation can cause this
first check the level of the coolant in the radiator. (do this when the engine is cold) if the level is low it will mean less coolant circulating through the system
second check the quality of the coolant
third have the system flushed out as their could be restrictions in the passages or the radiator
fourth--have you changed the engine thermostat? if that is opening late you won't have heat until it opens
fifth--don't know if you have a hot water shut off valve that stops the water flow to the heater core when the a/c is on; if you do check that valve to see that its open.
there's a way outside possibility that the water pump impeller is worn but thats a long shot

i'd suspect the engine thermostat should be changed

hope that helps

[MC]

sound like you need a new heater core.

if so. good luck, they are no fun, i have a s10 4by4
i had to remove all the dash. but usually you lose coolant when it goes bad......