I have a 2006 Honda Odyssey I bought new. Never wrecked. About 2-3 winters ago the heat quit working right it would just get cool to lukewarm. I took it to the dealer and they fixed it under warranty. Don't know what they did. It is doing the same thing again. Could it be a stuck thermostat? Temps are fine on the dash gauge. Coolant levels are good.

. Reverse flush the heater core.

. Drain the cooling system.

. Refill with a 50/50 mixture of the proper antifreeze and distilled water. Read your Owner's Manual on how to fill the cooling system to eliminate air. This is very important. Failure to do it right could cause the engine to overheat and blow the head gasket. I've seen this happen on Hondas.