Dual Zone Heat only works on one side
I have a 2005 Odyssey EX? with about 76000 miles on it. As soon as it got cold, we discovered that the Driver side heat does not work. The car has dual zone AC controls; the passenger heat works and the rear heat works. It is just the Drivers side that does not work. I BELIEVE that the air conditioning works fine, but it hasn't gotten hot enough for me to really verify that.
Honda has taken two shots at fixing it. First they said it needed a new thermostat. I was skeptical, but they ordered the part. When it came in, I asked what happens when it didn't work. The service guy chuckled, but of course it did NOT work. They spent another 4 hours fiddling with the computer and calling the Honda "help desk". Ultimately, they decided that the Heater Core needs to be replaced.
Has anyone seen this problem before? Does that make any sense to you guys? I mean, the passenger heat works fine, so what failure mode could cause the heater core to break so that the heat works on one side and not the other?
I realize that this is a huge pain in the butt to fix (and $$$ too). I just want to make sure that they do not take the car apart and figure out that they don't have the right parts to really fix the problem. Any advice you can give would be appreciated.
(I posted this in the Odyssey forum, but subsequent searches make me think that other Honda cars might have had a similar problem, so I am asking here. I've been to a couple of dealers, and no one has seen this before. Argh.)