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Discussion Starter #1
My front vents blow warm, not hot, and the rear doesn’t blow at all when set to heat. Ac works all around, I have enough coolant and I think the thermostat works. Any thoughts?
 

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What does your temp gauge show? If the thermostat is stuck open perhaps the coolant is not hot.
What yr is your Ody/
On my '03, there is a heater valve near the firewall just behind the engine. It is operated by a cable. You can also put your hand on the hoses at the valve to see if they are hot or not.
So, the rear fan blows on AC but not on heat?
Did this just start or has it been off and on for awhile?
Buffalo4
 

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Discussion Starter #3
temp gauge shows normal.
2004
“On my '03, there is a heater valve near the firewall just behind the engine. It is operated by a cable.” What do I need to look for - Broken or disconnected cable?
The hoses seem hot.
“So, the rear fan blows on AC but not on heat?” Yes. No air out the rear vents for heat but the blower is running. Switch to ac and it blows out the vents.
“Did this just start or has it been off and on for awhile?” I am turning my heater on for the first time since last winter/spring.

Someone thought both of my actuators are not working.

Thanks.
 

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“On my '03, there is a heater valve near the firewall just behind the engine. It is operated by a cable.” What do I need to look for - Broken or disconnected cable?
The hoses seem hot.
Okay, that's a good start.

If both hoses on either side of the valve are hot, it indicates insufficient flow through the valve. Three things could cause this:
  1. The valve could be corroded internally and so blocking the free movement of coolant. The only way to check it is to remove it. (Has the coolant ever been replaced with other than Honda coolant? An incompatible coolant could cause corrosion.)
  2. The valve is not opening fully or is misadjusted. Set the heater control to minimum and note the position of the lever on the valve. Next turn the heat to maximum and see if the lever has moved about 3/4".
  3. If #2 checks out, the valve could be broken free of the lever and stuck in a partially open position. Same check as #1.
Dave
 

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I have a similar problem with my 2002 Ody LX. The system worked great last year. I cycled it several times this summer at full temp and it worked well. It is getting cold now here in Georgia. I turned the climate control onto full auto and got cold air. AC seems to be cycling well (all summer at 90 plus daytime) but now not switching to the heater core. Both sides of that valve at the firewall are the same temp. I see, essentially, no movement in the cable that controls the valve.
I am planning to remove the cable from the valve today and test for free movement in the cable and valve.
Any other suggestions?
 

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I have a similar problem with my 2002 Ody LX. The system worked great last year. I cycled it several times this summer at full temp and it worked well. It is getting cold now here in Georgia. I turned the climate control onto full auto and got cold air. AC seems to be cycling well (all summer at 90 plus daytime) but now not switching to the heater core. Both sides of that valve at the firewall are the same temp. I see, essentially, no movement in the cable that controls the valve.
I am planning to remove the cable from the valve today and test for free movement in the cable and valve.
Any other suggestions?
Check for good movement in the valve also, after you take that cable off. Turn the lever on the valve all the way open (can't remember which way it is but there are only two full positions, either full ON or full OFF. When the coolant temp is hot, you should be able to get good heat when the engine is running.and the fan switch is turned on high.
Pretty easy to release that cable at the valve. It is kind of a friction clip that holds that cable sheath in place.
There is an actuator motor under the dash on the Drivers side under the dash near the center console that sometime causes that problem. Sometime it just takes removing it and cleaning some contacts, like a variable resistance with an arm going over many contact points. If you search in this forum, you should be able to find it. Not sure what search terms you need to know.
Buffalo4
 

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Okay, that's a good start.

If both hoses on either side of the valve are hot, it indicates insufficient flow through the valve. Three things could cause this:
  1. The valve could be corroded internally and so blocking the free movement of coolant. The only way to check it is to remove it. (Has the coolant ever been replaced with other than Honda coolant? An incompatible coolant could cause corrosion.)
  2. The valve is not opening fully or is misadjusted. Set the heater control to minimum and note the position of the lever on the valve. Next turn the heat to maximum and see if the lever has moved about 3/4".
  3. If #2 checks out, the valve could be broken free of the lever and stuck in a partially open position. Same check as #1.
Dave
If there is no coolant flow through the heater core, would both hoses be hot?
Buffalo4
 

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Buffalo4
Thanks for the response. I will let you know how it goes. In my case, there does not seem to be flow through the core and both hoses are the same temp when hot.
 

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I am fairly sure that when that lever is furthest from the firewall (towards the engine), it means it's OPEN.. (full hot)
But, there are only two extreme positions, one is for full heat and the other is for NO heat!!
Look at these posts : https://www.odyclub.com/threads/a-c-not-cool-enough-found-the-problem.154166/page-3#post-750509

If you put ' heater valve' (without the quote marks) in the search box (Search Community) you will get a lot of hits. (It should be at the top of most forums.).

Buffalo4
 

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If there is no coolant flow through the heater core, would both hoses be hot?
Buffalo4
No, not in the case of no flow. Result would be ambient air temperature from the heater.

But they would be hot if there is partial flow. Result would be warm air from the heater, which the OP is getting.

Dave
 

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Buffalo4
Thanks for the assistance. All is now running like new.
The valve (engine side) was sticky and had to be exercised and lubed but that was not the culprit.
The controller (passenger side on my 2002) was stuck on full air. I took the cable off and with slight hand pressure on the lever, cycled the temp dial between 60 and 90 on full auto. It only took 2 cycles before the controller freed up. After 10 more 60 to 90 and back cycles the controller was running smoothly. Reattached and adjusted the cable starting on the engine side.
Now the temp delivered is nearly exactly what the panel reads.
At the same time, I also replaced the cabin filter.
 

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Buffalo4
Thanks for the assistance. All is now running like new.
The valve (engine side) was sticky and had to be exercised and lubed but that was not the culprit.
The controller (passenger side on my 2002) was stuck on full air. I took the cable off and with slight hand pressure on the lever, cycled the temp dial between 60 and 90 on full auto. It only took 2 cycles before the controller freed up. After 10 more 60 to 90 and back cycles the controller was running smoothly. Reattached and adjusted the cable starting on the engine side.
Now the temp delivered is nearly exactly what the panel reads.
At the same time, I also replaced the cabin filter.
Happy to hear it is working OK. Nice troubleshooting!!
No, not in the case of no flow. Result would be ambient air temperature from the heater.

But they would be hot if there is partial flow. Result would be warm air from the heater, which the OP is getting.

Dave
Then, wouldn't both of them be hot with full flow?
Buffalo4
That controller might need some maintenance in the near future. I thought that controller (the one that operates the cable) was on the driver's side, but perhaps that was not the case on a 2002.
Buffalo4
 

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