Honda Odyssey Forum banner
1 - 20 of 21 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter · #1 ·
I've spent some time searching this forum for the answer, but most search results involve the A/C and not the heater.

I've have a 2009 Honda Odyssey EX with 155,000 miles. Coolant Reservoir is full. Coolant was changed in 2017 at 97,843 miles when the timing belt was changed. It does have Honda Coolant.

My wife is the primary driver of the van and told me today that the van is not heating up. The weather finally turn cold this week, so this is really the first time since last spring that we really need to run the heat.

I tested the heat and the blower is working properly, the blower is changing from front vents to floor vents to defrost just fine. But the air coming out from any of these vents is cold. This is both on the drivers and passenger side. I adjusted the temperature all the way up to "hi" and tried manual changing the setting and it didn't help.

The back vents in the ceiling do blow hot air. We are using that to warm up the car for the time being.

The temperature gauge is showing normal temperatures in the engine.

I did check what some people call the "Blend Door Actuator" which is mounted on the drivers side near the gas pedal. It appears to operate correctly. I can see the mechanism move when adjusting the temperature and I can see the cable move both inside the cabin and inside the engine compartment.

How should I go about debugging this issue. Where should I be looking?
 

·
Registered
2010 EX-L
Joined
·
5,253 Posts
There is a mechanical valve operated by a cable in the engine compartment near the center of the firewall. Check to see if that valve is operating properly. It is a valve in one of the heater hoses that controls the flow of coolant to the heater core. Perhaps this valve has failed closed. You might try manually operating the valve which may require detaching the cable.
 

·
Registered
2006 Honda Odyssey (EX)
Joined
·
6,447 Posts
First of all, run the self-diagnostic test on the climate control system (search the forum, there have been posts showing how to do this before) and see if there are any stored codes that can help give you a lead.
 
  • Like
Reactions: Nrajeff

·
Registered
Joined
·
13 Posts
Discussion Starter · #5 ·
In response to everyone’s questions so far:

1. The coolant level in the reservoir is about half way between min and max.

2. The valve in the engine compartment does move. When the heat is on, the cable is extended and the arm on the valve is to the left (as you look at it from the front of the car). When I turned on the A/C, the cable pulled in and the valve moved to the right. I did expect the valve to turn more than it did, but when I watched the motor from inside the cabin nothing seemed out of the ordinary.

3. I will run the diagnostic later today when the van is available and get back with you.
 

·
Registered
Joined
·
3,016 Posts

·
Registered
2010 EX-L
Joined
·
5,253 Posts
In response to everyone’s questions so far:

1. The coolant level in the reservoir is about half way between min and max.

2. The valve in the engine compartment does move. When the heat is on, the cable is extended and the arm on the valve is to the left (as you look at it from the front of the car). When I turned on the A/C, the cable pulled in and the valve moved to the right. I did expect the valve to turn more than it did, but when I watched the motor from inside the cabin nothing seemed out of the ordinary.

3. I will run the diagnostic later today when the van is available and get back with you.
FWIW, The screw that holds the arm to the valve was loose on my son‘s 2003 Honda accord. So even though the cable was moving the arm, the arm was not moving the valve because of the loose screw. This likely is not your issue but you may want to check and make sure the screw is tight.
 
  • Like
Reactions: Nrajeff

·
Registered
Joined
·
899 Posts
After car warm/hot feel upper and lower radiator hoses.
There should be a temp differential.
Are rad fans turning on, normally, as expected?

Feel heater hoses, in, and out, at fire wall.
Should be temp diff if heat on.

Is thermostat seized open?

Ever replaced radiator?
Ever replaced thermostat?
Was A/C working ok a few months ago?

@ 155k may need a thermostat.

JMT
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #13 ·
The radiator and thermostat have never been replaced. The only thing I had done on the system is the water pump / coolant change back when the timing belt was changed in 2017.

No problems with the A/C. My wife uses the A/C all the time, even when the vent would work fine. I imagine she used it a couple of weeks ago when it was 80 outside (a record high for that day in Nov).

As far as the thermostat goes, my guess is that it is working because:
1. The car temperature according to the gauge on the dashboard warms up normally. Correct me if I am wrong, but if the thermostat is stuck open, the car normally takes longer to warm up because the coolant is going into the radiator all of the time instead of only when needed. And if it was stuck closed the temperature would be high, which it is not.
2. The heat in the back works fine. I drove the van today and heat from the rear was enough to get the car warm inside, it just took a little longer than the front vent would have.
3. Even after driving for a while when the engine should have come up to temperature, the front vents were still cold. I would expect them to warm up some, but they aren't. The temperature has been around 40 the last few days.

I did attempt to use one of those infrared thermometers to measure the hose temperatures, but I didn't have much success. The one I own is a Harbor Freight special, and it is not very conducive to pointing it at the hose and reading it at the same time. I also believe it was picking up temperatures from things I wasn't pointing at, so I really don't trust the numbers. I will try again tomorrow.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #15 ·
Yes, once it warms up, the temperature gauge stays just below the middle, and doesn't fluctuate. It basically just touches the printed icon behind the temperature gauge.
 

·
Registered
Joined
·
15 Posts
I've spent some time searching this forum for the answer, but most search results involve the A/C and not the heater.

I've have a 2009 Honda Odyssey EX with 155,000 miles. Coolant Reservoir is full. Coolant was changed in 2017 at 97,843 miles when the timing belt was changed. It does have Honda Coolant.

My wife is the primary driver of the van and told me today that the van is not heating up. The weather finally turn cold this week, so this is really the first time since last spring that we really need to run the heat.

I tested the heat and the blower is working properly, the blower is changing from front vents to floor vents to defrost just fine. But the air coming out from any of these vents is cold. This is both on the drivers and passenger side. I adjusted the temperature all the way up to "hi" and tried manual changing the setting and it didn't help.

The back vents in the ceiling do blow hot air. We are using that to warm up the car for the time being.

The temperature gauge is showing normal temperatures in the engine.

I did check what some people call the "Blend Door Actuator" which is mounted on the drivers side near the gas pedal. It appears to operate correctly. I can see the mechanism move when adjusting the temperature and I can see the cable move both inside the cabin and inside the engine compartment.

How should I go about debugging this issue. Where should I be looking?
Have you checked the bend door actuators? The gears get stripped and they don't move the blend doors like they are supposed to. The part is about $30-35 to replace.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #19 ·
Happy Thanksgiving to everyone. I wanted to provide an update.

My friend and I decided to flush the heater core, because we couldn't figure out what else could be the problem. A clogged heater core could cause this issue and since the rear worked, it seemed like a possibility. We originally disconnected the 2 hoses at the engine that go to the heater core, and then used some low pressure air to push the coolant though the system, only to find out that there is a "t" connection in the hose that separates the hoses going to the rear heater core from the ones going from the front. So we weren't necessarily pushing coolant from the front. So we disconnected the hose at the T to make sure that we were only going to the front Heater Core. We were using the hose that did not have the valve, because we assuming that the valve side with the input and we wanted to use the output hose to force air in the opposite direction as it normally flows.

We ended up using air pressure, and then water, and then air pressure again. The original coolant came out. Then the water came out. So it didn't seem like the heater core was blocked. Some of you will say I should not have used water because it could leave mineral deposits, but it was a spur of the moment thing and we forced the water out of the heater core with air when we were done, so hopefully not too much water was left in the end to make any deposits.

Once we were done, we filled and bled the system. Unfortunately, it didn't help. Sill not heat from the front.

To Kmccance, I did watch the door actuator motor today. It is moving the wire that opens and shuts the heater value inside engine compartment, and it is also moving the black lever, which I believe is attached to the Blend Door. So when you say the "gears get stripped and they don't move the blend doors", are you referring to gears inside the white motor assembly that is mounted close to the brake pedal, and are you suggesting I replace that white motor assembly? From what I see it appears to work correctly, unless that black lever is not really attached to anything anymore and not moving the door.

I have considered the HVAC head unit be faulty. But I have doubts that it is the issue, because when I change from heat to cool or vs versa, the blend door motor changes position. The fans in crease and decrease speed when I change them, and the fans change position based on how I set them. So I seems like the HVAC head unit does what I ask it to do.

I guess I am at a loss right now on what it could be. Any other ideas?
 
1 - 20 of 21 Posts
Top