No heater function

This sounds like the blend door is not allowing the air to go over the heater core. There is a chance that the heater core is plugged but I would suspect the actuator first.

I attached the process on how to replace the front and rear one as you did not say if it was all vents or just the front or rear.

Let me know if you have questions.

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?

It sounds like you can be low on coolant even though the hoses are hot it could just be steam and not hot coolant.

Does the system have a coolant leak can you check the level?

Here are a couple of guides and a video to help you check it out.

https://youtu.be/GSE9skKnOgY

and

https://www.2carpros.com/articles/car-is-leaking-coolant

and

https://www.2carpros.com/articles/car-heater-not-working

Please run some tests and get back to us so we can keep helping you.

Cheers

Here is more information I found that will help

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.

(Check the diagrams below)

Do you think it could be the water pump?

If the water pump or cooling system has a leak you would most likely have 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?

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!

Heater not working, no heat at all and fan not working. I hear a click when I turn the blower on. It is coming from under the glove compartment.

You mentioned the fans starting too soon, its a sign the coolant level is low.

Also 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.

Good evening,

It may be the blower motor that may be the issue.

I will attach a wire diagram for you to view. You can check for power to the blower motor. It is a very common failure.

Roy

https://www.2carpros.com/articles/low-or-no-air-flow-from-vents

Service and Repair


1. Remove the right front door sill, the door opening trim, and the kick panel; pull the carpet aside.


imageOpen In New TabZoom/Print



2. Disconnect the connector from the blower motor.

3. Remove the three screws that secure the blower motor to the blower unit; remove the blower motor.

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!

Thank you so much Roy. I will have that checked immediately.

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.

You are welcome. We are always glad to help.

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!!

Yes, the control panle controls the air flow and if it is faulty, the air mix motor would not movde the blend doors to the correct position.

Remove the air mix motor and manually move the blend door linkages to the heater position to test if the heater works.

When you said no heat, it it blowing cold air as if the A/c Is being operated instead of the heater or there is insufficient heat?

The heater in my car car just blows cold air. Do you have any idea what it could be?

the water pump is leaking Im going to have to replace it! do you happen to know of any link where i can find the timing belt diagram..?

Check the heater hoses leading to the core. Both should feel hot to the touch with a warm engine. They connect to a control valve that opens/closes to allow coolant through. If it is bad you get no heat. If both are warm and the valve opens, then it is likely to be the air mix door or it is actuator that are faulty and not directing the air through the heater core.

The air mix door and motor are under the heater plenum toward the floor in the passenger foot well. You can watch it as you select hot/cold. If the linkage is moving but no heat it is probably a bad door, if the linkage is not moving it is a bad motor.

Here is a guide for what you are in for when doing the job less the timing belt.

https://www.2carpros.com/articles/water-pump-replacement


TIMING BELT
Removal

1. Disconnect negative battery cable. Turn crankshaft pulley so that No. 1 piston is at TDC on compression stroke. White mark on crankshaft pulley should align with pointer on front cover. Remove right front wheel. Remove lower engine splash shield. Move auto-tensioner to relieve tension, then remove the generator and power steering pump drive belt(s).

2. Support engine with a jack and wood block under the oil pan. Remove ground cable (if necessary), then remove engine side mount bracket. If necessary, remove dipstick tube from front of engine (discard "O" ring). Remove crankshaft pulley. See Fig. 1. ( A high toruqe impact wrench works but at times it might be rather stiff.

3.Remove upper and lower timing belt covers. See Fig. 2. If reusing timing belt, mark direction of belt rotation for installation reference.

4. Remove one of the battery clamp bolts from battery tray. Grind threaded end of bolt to a partial point (about 45-degree chamfer). Thread battery bolt as shown to hold timing belt adjuster in installed position (hand tighten ONLY). See Fig. 3.

5. If applicable, remove timing belt guide plate from front of crankshaft sprocket. Remove engine mount bracket from front of engine.

6. Remove idler pulley bolt and idler pulley, then remove timing belt.

Installation (New Belt)

1. Ensure that engine is at TDC. Align dimple on timing belt drive pulley with pointer on oil pump. See Fig. 4. Align camshaft pulleys with pointers on back covers.

2. Remove battery clamp bolt from back cover. Remove the timing belt auto-tensioner.

NOTE:
When compressing sealed auto-tensioners, compression pressure should not exceed 2200 lbs. (9800 N).

3. Place sealed auto-tensioner in press. SLOWLY compress tensioner until pin can be inserted through tensioner body, and insert pin. See
Fig. 6. Install auto-tensioner onto engine.

4. Install battery clamp bolt into back cover. Apply liquid thread lock to idler pulley bolt and loosely install idler pulley.

5. Install timing belt in counterclockwise direction in the following sequence:
Crankshaft pulley, idler pulley, front camshaft pulley, water pump pulley, rear camshaft pulley and tension adjust pulley. See Fig. 7. Ensure crankshaft and camshaft pulleys remained aligned with marks on back cover. Tighten idler pulley bolt to specification.

6. Remove stopper or pin from auto-tensioner. Remove battery clamp bolt from back cover, if necessary. Install engine mount bracket to the front of engine. If applicable, install timing belt guide plate with concave surface facing out. Install lower cover, then upper front and rear covers. Clean, then install crankshaft pulley. Lubricate crankshaft pulley bolt threads and install bolt. Tighten crankshaft pulley bolt to specification.

7. Rotate crankshaft about 5-6 turns clockwise to position timing belt on pulleys. Ensure crankshaft and camshaft pulleys are aligned at TDC. Crankshaft pulley White mark should be aligned with pointer on front cover. Remove rubber plugs from upper covers to check camshaft pulley positions.

8. If either camshaft is not at TDC, remove timing belt and readjust position. To complete installation, reverse removal procedure. Tighten all fasteners to specification. Adjust drive belts to proper tension.

Installation (Used Belt)
1. Ensure that engine is at TDC. Align dimple on timing belt drive pulley with pointer on oil pump. See Fig. 4. Align camshaft pulleys with pointers on back covers.

2. Apply liquid thread lock to idler pulley bolt, and loosely install idler pulley. If auto-tensioner has extended and timing belt cannot be installed, perform new belt installation procedure. If auto-tensioner has extended and timing belt cannot be installed, remove and compress auto-tensioner. Install auto-tensioner.

3. Install timing belt in counterclockwise direction in the following sequence:
Crankshaft pulley, idler pulley, front camshaft pulley, water pump pulley, rear camshaft pulley and tension adjust pulley. See Fig. 7. Ensure crankshaft and camshaft pulleys remained aligned with marks on back cover. Tighten idler pulley bolt to specification.

4. Remove battery clamp bolt from back cover. Install engine mount bracket to the front of engine. If applicable, install timing belt guide plate with concave surface facing out. Install lower cover, then upper front and rear covers. Clean, then install crankshaft pulley. Lubricate crankshaft pulley bolt threads and install bolt. Tighten crankshaft pulley bolt to specification.

5. Rotate crankshaft about 5-6 turns clockwise to position timing belt on pulleys. Ensure crankshaft and camshaft pulleys are aligned at TDC. Crankshaft pulley White mark should be aligned with pointer on front cover. Remove rubber plugs from upper covers to check camshaft pulley positions.

6. If either camshaft is not at TDC, remove timing belt and readjust position. To complete installation, reverse removal procedure. Tighten all fasteners to specification. Adjust drive belts to proper tension.

Please let us know

Cheers,

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, and also the fans start working too soon. Any ideas on what it could be?

Check to see if the hose going out of the heater core is hot. If not, you have a plugged heater core.

I checked that too, the heater core is fine! Its driving me crazy, I cant think of anything else!

IF you have hot coolant going through the heater core, then the blend door has to be the problem.

I have checked the DTC code and it says there is an error K air blend motor, door. I have checked the air blend motor on the drivers side and it is functioning. I checked the motor on the passenger and it is opening the heater hose valve. I checked the radiator fluid and it is at the proper level. I have checked the fuses and they are working. Thermostat is functioning as normal. Can you suggest something that I am missing?

Hi,

It sounds like you have checked nearly everything. If the blend air doors are working, the coolant if full, and the engine is at normal operating temperature, the next thing I would suspect is the heater core is plugged.

Take a look through this link and see if it helps.:

https://www.2carpros.com/articles/car-heater-not-working

Do me a favor. Start the engine, turn the heater on high, and allow the engine to reach operating temperature. Next, feel both heater core hoses. Both should be hot. If they are, then the problem is in the vehicle (likely blend air door). 4

If only one is hot, then the core is likely plugged. Here is a link that shows in general how one is replaced:

https://www.2carpros.com/articles/replace-heater-core

____________________________________

Here are the directions specific to your vehicle. The directions below correlate with the directions.

____________________________________

2004 Honda Truck Odyssey V6-3.5L
Heater Unit/Core
Vehicle Heating and Air Conditioning Heater Core Case Service and Repair Procedures Heater Unit/Core
HEATER UNIT/CORE
Heater Unit/Core Replacement

SRS components are located in this area. Review the SRS component locations, precautions, and procedures in the SRS section before performing repairs or service.

1. Make sure you have the anti-theft code for the radio and the navigation system, then write down the frequencies for the radio's preset buttons.
2. Disconnect the negative cable from the battery.

pic 1

3. From under the hood, open the cable clamp (A), then disconnect the heater valve cable (B) from the heater valve arm (C). Turn the healer valve arm to the fully opened position as shown.
4. When the engine is cool, drain the engine coolant from the radiator.


pic 2

5. Slide the hose clamps (A) back, then disconnect the inlet heater hose (B) and the outlet heater hose (C) from the heater unit. Engine coolant will run out when the hoses are disconnected; drain it into a clean drip pan. Be sure not to let coolant spill on the electrical parts or the painted surfaces. If any coolant spills, rinse it off immediately.


pic 3

6. Remove the mounting nut from the heater unit. Take care not to damage or bend the fuel lines and the brake lines, etc.
7. Remove the dashboard.
8. Remove the evaporator.


pic 4

9. Remove the mounting bolts and the heater unit.


pic 5

10. Remove the self-tapping screws and the clamp (A), then carefully pull out the heater core (B) so you don't bend the inlet and outlet pipes.
11. Install the heater core in the reverse order of removal.
12. Install the heater unit in the reverse order of removal, and note these items:
- Do not interchange the inlet and outlet heater hoses, and install the hose clamps securely.
- Refill the cooling system with engine coolant.
- Adjust the heater valve cable.
- Make sure that there is no coolant leakage.
- Make sure that there is no air leakage.
- For evaporator and A/C-related information, refer to evaporator removal and installation.
- Do the PCM idle learn procedure.
- Do the power window control unit resetting procedure.
- Enter the anti-theft code for the radio and the navigation system, then enter the customer's radio station presets.

______________________________

Let me know if this helps or if you have other questions.

Take care,
Joe