04 Pilot Has NO HEAT!!!!!

[beecho2]

Ok...Here is my deal and I am praying that someone can help me out! I changed timing belt and water pump about a month and a half ago and I have no heat in front or rear vents. The shop I took it to today used a laser thermometer to see the temps of the hoses going in and out of the heater core and it shows 175 in and about 140 out. The radiator is full and there are no leaks. Is it possible to have a massive air pocket or do I have to change out all hoses in the car. I was thinking maybe its not getting proper flow through the heater core. Whoever had the car before me didnt do a coolant flush cause it is all brown inside the radiator. Sorry for the long post, but I am in pa. and it is starting to get cold here in the morning and need it. Please Help!

[2010exl]

First clarify a few things....

Does the blower motor work on all speeds?

Did the heat work before the timing belt change?

By brown do you mean the coolant is rusty and gritty?
If so, is it still rusty even after the water pump change where new coolant should of been installed?

[theirishscion]

Seems like you should be seeing some heat if there's a 35 degree drop between the coolant going to the heater core and returning from it.

Are you confident that the valve that controls water flow is working properly? Having both heater cores clog simultaneously seems unlikely. What temperature was the rest of the coolant in the system? I'm not sufficiently familiar with your model to know if air pockets are a likelihood, though I'd sort of doubt it. The recent pump change does make that seem more likely though, assuming the heat was working fine before that.

More to the point, did the shop you took it to actually diagnose anything? What were they getting paid to do?

[beecho2]

Yes the blower motor works! And as far as I know the heat worked before. I bought it in June so it was hot and didnt really bother to check. And the coolant was brown and gritty when the water pump was done and new coolant added. The garage didnt charge me cause it is a personal family member who owns it and basically came to the conclusion that there is bad flow somewhere they just dont know where. The heater control valve is working properly cause they checked that.

[2010exl]

If there was an air bubble...it usually clears in a few minutes of driving as you vary the engine speed. In some cases, it is necessary to raise the front of the vehicle very high to help clear the air pockets, but this is a general rule, not necessarily needed for the Pilot as far as I know.

Do you know if the car is up to normal temperature? You can use a scanner with "live data" capabilities. You should see close to 200 degrees for normal engine temp.

Even if it was low, like 160 or 170 degrees, you should still be able to get warm air from the vents. A new thermostat would help bring the engine up to temp if it is running too cool.

You can check the heater hoses your self with the backyard mechanic method..... After 20 minutes of driving, turn the fan on high and one hose should be too hot to keep your hand on it for more than a few seconds. The other should be cooler. If this return line is very cool, a reverse flush of the heater core may be necessary.

The final place to look would be the blend door or heat control valve under the dashboard. I am not sure which your model has but the temp knob on the dash control should open and close either one to allow heat to flow when needed. I can look up what it has and will repost here shortly.

[beecho2]

There is also a new thermostat which I forgot to mention. Are you talking about the doors not opening to allow proper heat into vehicle? Also which hoses are you talking about checking? i checked the upper and lower radiator hoses and they both are about 170-180 in temp. I am just at a total loss of whats going on, I dont know if the heater core is bad or not but i should still have heat in the rear, correct?

[beecho2]

by the way 2010exl, mine has a temp control valve right below the heater core by the firewall which is working cause the cable is turning it when the knob in the car is turned to hot/cold

[2010exl]

The hoses you need to check are the smaller hoses that go to the heater core. One of them is attached to the heat control valve you mentioned.

I checked, and the Pilot also has a blend door mounted to the air box under the dash, it looks like it is on the passenger side. There is a rod attached to it, and it should move as the temp knob is moved from cold to hot.

You may need to remove some panels under the dash to get access to it.

There is an electrical connector with 7 wires attached to it. If it doesn't move, try tapping it lightly while you move the heat control knob.

[2010exl]

You say that you can see the cable move on the heat valve under the hood near the firewall.

It turns out that the blend door motor also controls that cable. So if that cable is moving, then the blend door motor is probably working properly.

Another item to check is that same valve under the hood. Make sure the heater hoses attached to either side are hot and are the same temp. If one side is significantly cooler than that valve may be broken internally, not allowing coolant to flow even though the cable is moving.

Can you clarify "no heat" again.....is the air flow cold like outside temp cold, or just warm?

[beecho2]

It is just warmer than outside temp, but its definitely not hot enough to keep you warm when it gets below 50 degrees

[beecho2]

And we did check those hoses and the inlet hose was about 180 degrees and the outlet was about 145-150

[2010exl]

Did you try removing the pollen filter and see if there is any change in air temp?

[2010exl]

I checked the procedure for bleeding the cooling system, nothing special there. Just run the engine at various speeds while changing from cold to hot on the climate control, stopping every few minutes to top off the coolant.

Since your coolant level isnt dropping, the air bubbles have been purged, according to the bleeding procedure.

I would say you need to flush the heater core. The big temperature drop you see on the return hose may indicate the the heater core is partially plugged and not moving enough coolant to provide adequate heat.

Is the air warmer is you run the fan on the lowest speed?

[94eg!]

Definitely check the cables that move the blend doors under the dashboard. Just because the motor is moving the water valve, it doesn't mean something didn't happen to the cables that move the blend doors. If the heater hoses are both getting hot, then your definitely getting hot coolant into the heater core.

Is the heater core in the back seat working?

Of course if there was lots of corrosion in the cooling system, it could be a blockage inside the heater core. But the return hose from the core should not bet getting that hot in that case. I am inclined to think it's a blend door issue.

[rocky]

Easier to park the car in your driveway. Have a gallon of ready mixed coolant available.

With a cold engine, open the expansion tank bottle. Fill to Max mark.

Start engine with heater on Max setting and watch as the air bubbles appear. Top up coolant as necessary. This will take time to pull off but its worth it.