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Discussion Starter #1
I have a 2009 Honda Odyssey with no heat on the drivers side. I have checked the resistance on the in-car temp sensor and that seems to be good. Is there supposed to be air coming down the tube to the sensor?

I can see the linkage move on the air-mix motor as well as on the heater control on the firewall. From other posts I am wondering if my heater core is plugged. I don't really want to replace the heater core? Can it be flushed with a garden hose? Any help would be appreciated. Thanks.
 

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For the home mechanic, it's rather difficult to flush just the heater core. It would involve draining most of the coolant from the vehicle, disconnecting the heater core at the firewall (haven't looked under there at my Ody yet, but most FWD vehicles have enough stuff shoehorned into the engine compartment to make the connections back there hard to access), connecting one side up to a water source, and catching the flushing fluid/water from the other side. Then re-connect the heater core at the firewall and try things out.

Before you go through that, you may want to warm the vehicle up to operating temp, turn the heat on full hot, and then either:
a) carefully rev the engine in park/neutral up (3-4000 rpm should be enough) for short spurts
b) take it on a drive where you do some hard accelerating

Sometimes that will turn the water pump hard enough to clear a chance obstruction from the (hard to get to) heater core. It would still be wise to flush the radiator and the engine block, but the connections for those are usually a bit more accessible.

nate
 

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Steep hill climbs at speed sometimes help clear air bubbles from the cooling system.

If you are getting any heat in the cab at all I bet your core has proper flow. If not check the heater valve. The core is not always hot the way it is in some other vehicles. Does the hose past the valve get hot after opening?

There are two air mix control motors. One for each side. Are you looking at the right one?

Have you run the AC system self diagnostic test? FSM 21-8 in my 2006 FSM.
 

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Discussion Starter #5
coolant level seems to be ok and I'm getting heat from the passenger side and in the back. Its just the drivers sides where it continues to blow cool air. I need to get out and feel the hoses to see if they are both getting hot.

Is the air mix motor what controls the heater valve cable?
 

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Is the air mix motor what controls the heater valve cable?
No.

There is only a single heater core so if you are getting passenger heat then the core and valve are working fine.

Each side has a separate Air mix motor that controls a door inside the unit to direct air flow. That where I would focus.
 

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No.

There is only a single heater core so if you are getting passenger heat then the core and valve are working fine.

Each side has a separate Air mix motor that controls a door inside the unit to direct air flow. That where I would focus.
+1 to that. Given you have heat, your heater core is fine. There's no way it would be plugged on a 2009 unless you had some type of major coolant contamination.

Something is up with the blend door actuator(s).

Joel
 

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Discussion Starter #9
the airmix motor seems to be working the heater value cable as well as flipping a door which I am assuming is an airmix door, so now I am wondering if there is another door somewhere I should be looking at or where to look next.
 

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I assume you have checked the dash vent doors themselves since they can be opened and closed manually ?
 

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Discussion Starter #11
yes, I'm getting air blowing through, its just not heated.

Does anyone think this could be due to air in my water lines? water pump has been replaced so there has been opportunity to have the system opened up. What is the best way to be sure there is no air in the system?
 

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I know this is an old thread but I thought I would ad my 2 cents if it helps anyone searching. My 2006 was slowly losing heat over the last year or so. Engine heat was normal and the rad reservoir tank was half full. When the engine was hot the hoses to the heater core were not getting hot. The cable moved the heater valve fine and the heater valve seemed to work ok. Every so often I would get a whiff of antifreeze smell but could not find a leak. We have had almost no heat at all this winter. Yesterday the antifreeze smell got very strong in the cabin so I looked under the hood. The rad was leaking quite badly from a hole at the very top of the rad right under the filler tube and cap. The overflow reservoir still was half full. I opened the rad cap and could not see any fluid. I put 3.5 liters in the rad and now I have lots of heat. New rad is on order. What I think was happening was that the rad got a pinhole and I would loose coolant as I drove. Then instead of sucking some coolant from the reservoir as it cooled it sucked air. I could still see coolant in the reservoir and could see no leak so I assumed there was lots of coolant in the system. Hope this did not damage the engine. Deepdezel was right. The coolant just needed to be checked.
 

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havhe driver side no heat issue also

I have a 2009 odyssey EX-l that has very little heat coming from the driver side heating vents...the passenger and the rear both put out the usual amount of heat. I replaced the air blend on the drivers side and can see it cycle and move the connected blend door in the vent system...but still no heat. whats the next step? i'm thinking flush the heater core?
 

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Before you go to extremes--check your antifreeze level.
 

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I have a 2009 odyssey EX-l that has very little heat coming from the driver side heating vents...the passenger and the rear both put out the usual amount of heat. I replaced the air blend on the drivers side and can see it cycle and move the connected blend door in the vent system...but still no heat. whats the next step? i'm thinking flush the heater core?
Similar symptoms on a 2005 EXL for 2+ years. I have gone through all the usual gyrations inspecting/removing/testing air door actuators (all good), verifying coolant levels, flow valve operation, thermostat, etc. Passenger side and rear are fine. Summer cooling fine. There is a TSB (14-063) for the 4th gen CR-V that addresses this very problem and apparently applies to older Accords as well. I am planning to back flush the core with CLR this weekend. My hesitation stems from 325K miles and not wanting to damage the core. Doing plenty of research and planing to minimize the potential. I initially rejected the idea given different engines but it's possible the same type, if not source, of contamination afflicts 3rd gen Odysseys.

The following threads may be if interest (newbie so can't post links; Google for results)
- 2008 Accord No Heat on Driver Side only (Drive Accord Forums)
- Dual Climate, No Heat on Driver's Side (Drive Accord Forums)
- 2012 Honda CRV LX heater core (Honda CR-V Owners Club)
 

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I have a 2009 odyssey EX-l that has very little heat coming from the driver side heating vents...the passenger and the rear both put out the usual amount of heat. I replaced the air blend on the drivers side and can see it cycle and move the connected blend door in the vent system...but still no heat. whats the next step? i'm thinking flush the heater core?
Similar symptoms on a 2005 EXL for 2+ years. I have gone through all the usual gyrations inspecting/removing/testing air door actuators (all good), verifying coolant levels, flow valve operation, thermostat, etc. Passenger side and rear are fine. Summer cooling fine. There is a TSB (14-063) for the 4th gen CR-V that addresses this very problem and apparently applies to older Accords as well. I am planning to back flush the core with CLR this weekend. My hesitation stems from 325K miles and not wanting to damage the core. Doing plenty of research and planing to minimize the potential. I initially rejected the idea given different engines but it's possible the same type, if not source, of contamination afflicts 3rd gen Odysseys.

The following threads may be if interest (newbie so can't post links):
- 2012 Honda CRV LX heater core [CR-V Owners Club]
- 2008 Accord No Heat on Driver Side only [Drive Accord Honda Forums]
- Dual Climate, No Heat on Driver's Side [Drive Accord Honda Forums]
 
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