No heater

Tiny
BOBMSS
  • MEMBER
  • 2003 HONDA ODYSSEY
  • 230,000 MILES
I have the van listed above with heat issue. My van does not have AC. When I turn the heat, cold air comes up. I first took it to mechanic where he changed the the heater valve but still no heat, then he flushed the heater core, the heat came up fine that day but the next day there was no heat. I changed radiator where there was leak and I changed thermostat too. I did not flush heater core when thermostat replaced though. I should mention that both heater core lines are equally hot based on the mechanic, does this that mean I would need to change the heater core? Please help.
Tuesday, December 11th, 2018 AT 10:33 AM

16 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
If both heater core hoses are equally hot, then that indicates that the heater valve is working and that the core is not clogged. Basically, it implies that the problem is elsewhere. Maybe it is in the blend air door actuator(s), the blend air door itself, or the HVAC control unit (the control board in your console). The blend door (aka air mix control door, as Honda calls it) basically directs the incoming air either to heat it or cool it, depending on your choice. It is not uncommon for the actuator that operates those doors to go bad and have the door stuck in whatever position it happens to be in at the time.

I am attaching a diagram indicating where the air mix control motor is on the HVAC assembly box and some instructions on how to test and replace the motor. If you can get to the motor, then run the test on it and let us know the results. The HVAC box is located behind the center console. Unfortunately, I do not have much information on how to access the air mix door motor or anything like that, so you will have to wing it.

Also, if your van has a navigation system, or a dual zone climate control (where the front passenger and driver can have different temperature settings), then please let me know that. I may have to do more research to get you the correct information. And the VIN# would be helpful too. Thanks and good luck. Let us know what you find.
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Tuesday, December 11th, 2018 AT 12:07 PM
Tiny
CCFIXIT4U
  • MEMBER
  • 1 POST
  • 2002 HONDA ODYSSEY
I have a 2002 Honda Odyssey my heater is not getting warm or hot but the rear heater is getting hot just like it should I am assuming they're both on the same system I believe they are don't know what the problem is if anybody could help please do so thanks
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Monday, December 14th, 2020 AT 7:53 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check coolant level first. Check to see if your air mix motor works and or the linkage has fallen off check mode door for proper movement. Check out the diagrams (Below). Please let us know what happens.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
GHONDAW
  • MEMBER
  • 1 POST
  • 2002 HONDA ODYSSEY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 82,000 MILES
The coolant is full. The fans work. With the temputure
set at 85 deg their is no heat. I think the heater control is sticking. How can I free it up.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi ghondaw,

Check if both heater hoses in engine compartment are hot when heater is turned ON. If yes and tyou do not have heat, the most likely cause would be the air mix motor, either it is faulty or stuck.


https://www.2carpros.com/forum/automotive_pictures/192750_AirMixMotor02OdysseyFig78_1.jpg

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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
JVAKMC94
  • MEMBER
  • 2 POSTS
  • 2000 HONDA ODYSSEY
I have a problem with the heater in front not blowing hot air. The rear works good but the front is Luke warm. I have checked the blend door and the motor, both seem to be working good, I've bled what I think is all the air out of the system when I flushed the radiator. If this helps, when I looked underneath where the blend door is, when the temp is turned up all the way the arm is not going all the way to the end of the track for the blend door. It looks like it is leaving it open just a little. Could this be the motor that controls opening and closing the door or the climate control panel?
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Have you checked to see if both the heater hoses going to the heater core at the firewall are getting too hot to hold?
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
JVAKMC94
  • MEMBER
  • 2 POSTS
Sorry for not getting back sooner, but no. The hoses are warm but not too hot to touch. Both the front and rear are blowing warm but not hot. Could the heater core be so clogged that I need to flush it itself?
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Could be but usually when the heater core is clogged one hose will be too hot to hold while the other hose is cool to warm.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
THOMSCOTT
  • MEMBER
  • 1 POST
  • 2000 HONDA ODYSSEY
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 195,000 MILES
We have lots of heat in the rear of the van but the front dfefrost only blows cold. Even when set to heat the front still only blows cold air

updated 1-6-10

Where do I find the air mix motor?
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi thomscott,

The front air mix doors are not operating correctly causing the problem. Check if the air mix motor is working when the heater is turned on.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
The air mix motor is located on the heater housing under the dash.


https://www.2carpros.com/forum/automotive_pictures/192750_HeaterAssy00OdysseyFig04_1.jpg



If you have further questions, please reply to this post using the reply to question link below so that notification would be sent to me and I can get to you as soon as I am online.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
YYALNIF
  • MEMBER
  • 2 POSTS
  • 2000 HONDA ODYSSEY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 136,000 MILES
My van has very little heat coming from the front and no heat blowing in the back. There is air flow but not the temperature it should be. We had a new radiator and thermostat installed in the summer. A friend told me to put 2 tbsp of powersteering fluid in the radiator to try to loosen up the damper doors in case they were stuck, but the radiator is so full even when I start the car that it wont hold even two tbsp of fluid. Is the heater core stopped up? Is my radiator circulating the antifreeze? What can I check to fix this problem? It is getting cold outside and my wife is unhappy.
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
I would NOT add tranny fluid to the radiator !
Check and replace the thermostat
if its a blend door it will work in the back not in the front
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
YYALNIF
  • MEMBER
  • 2 POSTS
I do have a check engine light on the van that is telling me the cadilatic converter is not working properly. Could this be that the engine is not getting hot enough to cause the converter to not work as well as the heater because the engine is not getting hot? If so what should I do? Check the thermostat or what?
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Monday, December 14th, 2020 AT 7:54 PM (Merged)
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Engine not getting hot thermostat is bad
replace the thermostat
catalytic converter does not effect your heater
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Monday, December 14th, 2020 AT 7:54 PM (Merged)

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