I'm only getting lukewarm heat from my 2002 Odyssey. The engine temperature is constant, so I'm betting its not the thermostat. I've checked the valve in the engine compartment, and it is working fine. I've felt the hoses on the heater core, and both are hot. The lines to the rear heater are both hot. I've watched the linkage on the blend door(I'm pretty sure I'm looking at the correct piece) and it moves smoothly. I've run the engine through many heat-up, cool-down cycles hoping to push out any air in the cooling lines, but it has proven fruitless. Last week I found a small hole in the hose going from the water pump to the tee connnector and replaced it. When I did this I thought I had found the problem. After a full day of doing heat-up and cool-downs at no more than 1500 rpm, I was getting hot air. I thought the problem was fixed. But the next day, the air was lukewarm again. One more piece of info. The rear heater is blowing lukewarm in the vent right beside the passenger door, but dead cold from the vent at the rear fold down seat. I've been considering backflushing, but it doesn't make sense that I would get hot air when I was working on it? Any ideas?

Well...I've replaced the thermostat, forward flushed the cooling system, backflushed the front and rear heater cores, and checked the anti-freeze/water ratio. I'm still getting the same result. If I let the car heat up at between idle and 2000 rpm (letting it get REALLY hot) I get hot air, both front and rear. If I start driving it, everything goes luke-warm. It was 40 degrees here yesterday and my family was wearing their jackets in the van. The water gauge is still registering rock solid at a little less than half. The flushes went fine, becoming clear after less than 1 minute (I flushed for a total of 1 hour, varying between hot and cold flush, and forward/reverse flush. Any other ideas why this could be happening??? Well...I've replaced the thermostat, forward flushed the cooling system, backflushed the front and rear heater cores, and checked the anti-freeze/water ratio. I'm still getting the same result. If I let the car heat up at between idle and 2000 rpm (letting it get REALLY hot) I get hot air, both front and rear. If I start driving it, everything goes luke-warm. It was 40 degrees here yesterday and my family was wearing their jackets in the van. The water gauge is still registering rock solid at a little less than half. The flushes went fine, becoming clear after less than 1 minute (I flushed for a total of 1 hour, varying between hot and cold flush, and forward/reverse flush. Any other ideas why this could be happening???

Well...I've replaced the thermostat, forward flushed the cooling system, backflushed the front and rear heater cores, and checked the anti-freeze/water ratio. I'm still getting the same result. If I let the car heat up at between idle and 2000 rpm (letting it get REALLY hot) I get hot air, both front and rear. If I start driving it, everything goes luke-warm. It was 40 degrees here yesterday and my family was wearing their jackets in the van. The water gauge is still registering rock solid at a little less than half. The flushes went fine, becoming clear after less than 1 minute (I flushed for a total of 1 hour, varying between hot and cold flush, and forward/reverse flush. Any other ideas why this could be happening??? Well...I've replaced the thermostat, forward flushed the cooling system, backflushed the front and rear heater cores, and checked the anti-freeze/water ratio. I'm still getting the same result. If I let the car heat up at between idle and 2000 rpm (letting it get REALLY hot) I get hot air, both front and rear. If I start driving it, everything goes luke-warm. It was 40 degrees here yesterday and my family was wearing their jackets in the van. The water gauge is still registering rock solid at a little less than half. The flushes went fine, becoming clear after less than 1 minute (I flushed for a total of 1 hour, varying between hot and cold flush, and forward/reverse flush. Any other ideas why this could be happening???