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Dual Zone Heat only works on one side

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Old 10-15-2009, 07:12 PM   #1
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Default 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.)

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Old 10-16-2009, 09:09 PM   #2
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Default Re: Dual Zone Heat only works on one side

THat does not make a lot of sense. It sounds like a problem in the drivers air mix door/motor. I am not looking at the van, but a heater core sounds like a huge waste of time and money for both parties. YOu can see if the drivers air mix motor is working or not when you switch it from cold to hot by placing your hand on the driver's air mix motor itself.
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Old 10-16-2009, 09:43 PM   #3
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Default Re: Dual Zone Heat only works on one side

hmmmm....did they even try to replace the hvac control unit to see if that was the problem? i am sure they have a 05 ody out on there lot somewhere so they could swap parts.....it possibly could be the heater core if say in ur situation the drivers side half of the heater core was blocked and no coolant was flowing to it therefore there wouldn't be any heat on that side.....there r also possibilities that a certain multiplex system may have failed....but first things first like kwayracing said is check operations of the air mix doors...did they even do this????
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Old 01-22-2010, 07:04 PM   #4
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Default Re: Dual Zone Heat only works on one side

I have good news and bad news. The good news is that we did figure out what caused this problem. The bad news is that it was really expensive to fix.

Anyway, Honda looked at mine forever and ultimately said it was the heater core. This made no sense since the heat still worked on the passenger side. My shop agreed and felt it was the air mix motor. This shop HAS seen this problem, and they thought that was going to be the problem. However, they had the ability to stick a camera down there and they told me that everything was working just fine. Ultimately, it WAS the heater core. This part is not that expensive, but the labor cost is pretty high - at least 8 hours - because they have to take the dash completely apart to get to the parts regardless of whether it is the air mix motor or the heater core.

My mechanic was curious about the whole problem, so they sawed the heater core in half. They said that it is designed in such a way that one side could get heat while the other is clogged. Indeed, one half of mine was clogged with sediment or something similar. I thought I had had mine flushed, but apparently not (or not good enough).

It cost me close to $1000 at this shop. The dealer wanted more like $1400.
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