Mechanics

HEATER

2004 Honda Odyssey • 6 cylinder 2WD Automatic • 100,000 miles

My 2004 honda odyssey heater wont heat, neither the front or the back! I changed the thermostat, I purged the system, I changed the cabin air filter and still no heat, the door that changes the settings from hot to cold works fine too, the hose from the heater core does get hot, so Im assuming the heater core its working, the only thing I did noticed its that the fans start working too soon. Any ideas on what it could be?
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Franxua1
December 31, 2010.



Is climate control manual or automatic?
Are both heater hoses hot?
Does vehicle have navigation system?


KHLow2008
Jan 1, 2011.
Its automatic, (electric) and yes both hoses are hot! And no it doesn't have navigation system!


Tiny
Franxua1
Jan 1, 2011.
Such faults are usually due to a problem with the air-mix motors or blend doors. System is equipped with self-diagnostics. Perform the following test to see if you are abe to retrieve any trouble codes.

HOW TO RETRIEVE A DIAGNOSTIC TROUBLE CODES
The climate control unit has a self-diagnosis function. To run the self-diagnosis function, do the following: 1 Turn the Ignition switch ON (II).

2. Press the AUTO button and then press the OFF button. Continue to hold both buttons down for 1 minute.

If there is any abnormality in the system the temperature Indicator will light up the segment (A through N) corresponding to the error. The temperature indicator will then alternate every second between displaying "88" (all segments lit) and the error code segment (A through N).

NOTE: The system will only display the DTC when the AUTO and OFF buttons are pressed if you release the buttons the display will go blank. To return the display, simply press the AUTO then the OFF buttons again.

To determine the meaning of the DTC, refer to the DTC Troubleshooting Index. If there is no abnormality the segment will not light up.

Cancelling the Self-diagnosis Function

3. Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work run the self-diagnosis function again to make sure that there are no other malfunctions.


KHLow2008
Jan 2, 2011.
Ok I tried Retrieving a Diagnostic Trouble Code, but nothing, appeared on the screen! Any other options, do you think it could be the water pump?


Tiny
Franxua1
Jan 2, 2011.
If the water pump or cooling system has a fault, you would most likely have have overheating issues instead of no heat.

Did you back flush the heater core when replacing the thermostat?

You mentioned purging the the system, did you recheck coolant level when engine cooled down?

When bleeding the system were the heater turned to maximum heat?


KHLow2008
Jan 3, 2011.
Yea I backed flushed the heater core, and yea I checked the coolant, it was fine, about the heat yea when I did the bleeding the heater was turned at maximum!


Tiny
Franxua1
Jan 3, 2011.
You mentioned the fans stsrting too soon, which fans are you referring to?

Check the air mix motor and its linkages for proper operations.

Switch between A/C and heater and note if the air mix motor are moving and note if the linkages are moving or binding.

Remove the air mix motor to check if necessary.


KHLow2008
Jan 3, 2011.
The fans at the front of the car, but I just realized that when they were starting too son it was because the car didn't have enough anti freeze! Now they are working fine! But still no hot air.


Tiny
Franxua1
Jan 4, 2011.
With heater connections to rear of vehicle, there could be a lot of air trapped in system and requires quite some bleeding process.

Redo the bleeding of the cooling system again. Turn heater to max heat and run engine for 5 minutes with radiator cap off. Top up coolant level if it goes down.

Stop engine after 5 minutes. Close radiator cap and run engine till operating temperature. Stop engine and allow to cool. Remove radiator cap to check coolant level. If low repeat bleeding process. Ensure recovery tank has sufficient coolant.

If heater both hoses are hot after 5 minutes of engine running, check the air mix motor and linkages.


KHLow2008
Jan 4, 2011.
I have a question, do you think it can be the climate control system, because I just noticed yesterday that the screen that it supposed to tell you the temperature and the position on which you want the air flow doesn't light, I mean it does show the temperature and the position, but it doesn't light, I'm thinking it could be that. Do you think that could be an option!


Tiny
Franxua1
Jan 4, 2011.
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