Chevrolet Repair: 2001 Chevy Venture heating prob., chevy venture, themo

Question
Heat when the van is warmed up in the mornings doesnt come on until I am driving at least 35 mph and then it is sporadic, off and on all the way to work, and that is after a good 20 minute warm up. No check engine lights come on so I don't have a clue. Any ideas? Thank you very much!

Answer
Kathy,
You should have the cooling system flushed, and the thermostat replaced. Also they should flush the heater core as well. If you have a dirty cooling system, bad themo or a plugged heater core, you will get some heat but not much. Hope this somewhat helps,, stay warm this winter,, and good luck..