I am hoping someone here has insight into these things. 2006 Odyssey with weird situation.  Cold air blows through vents and all, but no heat. But here is the kicker. 
Air gets hot within 5 minutes of vehicle moving on the road.  If I pull the vehicle to the side or vehicle slows down, the hot air becomes cold.

Any insights into whats happening ? Appreciate it. 

 

Check your coolant levels, if it's good then you may have a clogged heater core or a clog in the coolant circuit.  When the engine is revving, it provides more pressure so that may explain why heat is on only when moving.  It could also be air in the system.  There's a way to bleed it out but I'm not sure how on your odyssey.

It's possible your heater control valve is stuck partially open and when you're revving the engine while driving, water pushes through the valve, at idle, it holds the water off.

That'd be my first guess.   Other than that, there's maybe something going on with your blend door.

Thanks both. What is the medium that carries "heat" generally. Is it the water or coolant ? Sorry for silly questions. 

28 minutes ago, jackandjill said:

I am hoping someone here has insight into these things. 2006 Odyssey with weird situation.  Cold air blows through vents and all, but no heat. But here is the kicker. 
Air gets hot within 5 minutes of vehicle moving on the road.  If I pull the vehicle to the side or vehicle slows down, the hot air becomes cold.

Any insights into whats happening ? Appreciate it. 

 

On Fresh air or recirculated?

Just now, Zeke said:

On Fresh air or recirculated?

I tested with recirculated as outside air is pretty cold. I can test with fresh air and see behavior.  Why do you ask ? 

1 minute ago, jackandjill said:

Thanks both. What is the medium that carries "heat" generally. Is it the water or coolant ? Sorry for silly questions. 

Coolant, heater core is a mini radiator inside ish

Just now, Zeke said:

Coolant, heater core is a mini radiator inside ish

How does water come into picture that @Malsua mentioned ?

Idk, easy be thermostat stuck open?

Just now, Zeke said:

Idk, easy be thermostat stuck open?

If the thermo was stuck open, it would take forever to heat up.

When was the last time you serviced the cooling system, i.e flush and fill or even just checked the levels?

Just now, jackandjill said:

How does water come into picture that @Malsua mentioned ?

That be the antifreeze/ coolant bud

” water” is laymen 

Just now, Scorpio64 said:

If the thermo was stuck open, it would take forever to heat up.

When was the last time you serviced the cooling system, i.e flush and fill or even just checked the levels?

But the water pump is tied to Rpm’s. And if you ant pumping to heater core...

2 minutes ago, Scorpio64 said:

If the thermo was stuck open, it would take forever to heat up.

When was the last time you serviced the cooling system, i.e flush and fill or even just checked the levels?

never :-). I just asked buddy for some time to check the cooling system level. 

Full! I mean full diagnostic report on the issue!

So how does this generally work ? 

Is the hot coolant from engine redirected to heater core instead of radiator ?   If so, what the cooling system or its levels  got to do with this ? 

1 minute ago, jackandjill said:

So how does this generally work ? 

Is the hot coolant from engine redirected to heater core instead of radiator ?   If so, what the cooling system or its levels  got to do with this ? 

How do you cool an engine?

1 minute ago, Zeke said:

But the water pump is tied to Rpm’s. And if you ant pumping to heater core...

low or high rpms, coolant will still make it to the core if the system is not blocked/clogged.

Just now, Scorpio64 said:

low or high rpms, coolant will still make it to the core if the system is not blocked/clogged.

Yeah but he gets hot then not... big bore bikes would over heat in tight stuff cause revs aren’t high... fluid dynamics 

@carl_g

antifreeze/coolant runs through the radiator the engine and the heater core if heat is turned on.  It is prevented from moving through the circuit by a thermostat, that is actually a heat activated valve, when the engine is cold.  There is also a reservoir that holds "extra" coolant.  That is where you can check the coolant level by eyeballing it.  When the coolant heats up it expands and some of it may bleed off into the reservoir, that's normal.

Bad mixing valve, low coolant level, bad thermostat. My call

2 minutes ago, Zeke said:

Yeah but he gets hot then not... big bore bikes would over heat in tight stuff cause revs aren’t high... fluid dynamics 

@carl_g

My money is on air in the system or a clog in the system.  Needs to start with checking coolant level.

Full shade tree.

1 ck coolant level 

2 replace thermostat 

3 seek professional help

1 minute ago, Zeke said:

Full shade tree.

1 ck coolant level 

2 replace thermostat 

3 seek professional help

One of the actual experts should be along shortly. #3 should really be #1.

Clearly, it is the Flux Capacitor.

1 minute ago, blksheep said:

Clearly, it is the Flux Capacitor.

Needs to add some elbow grease.

13 minutes ago, Scorpio64 said:

One of the actual experts should be along shortly. #3 should really be #1.

Lol!

12 minutes ago, Scorpio64 said:

One of the actual experts should be along shortly. #3 should really be #1.

 

Just now, Zeke said:

Lol!

Well, it's true.  I'm just basing my guesses from my own experiences.  There are bunches of other things that could be the problem that only an expert can diagnose.  (but i'm probably still right )

2 minutes ago, Scorpio64 said:

 

Well, it's true.  I'm just basing my guesses from my own experiences.  There are bunches of other things that could be the problem that only an expert can diagnose.  (but i'm probably still right )

Full! Full forensic report is required to settle this!

 

Ok. checked the coolant level and I canNOT see any coolant in the reservoir. F.

Just now, jackandjill said:

Ok. checked the coolant level and I canNOT see any coolant in the reservoir. F.