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Discussion Starter #1
My heater no longer blows hot air. Discharge air is cool and sometimes luke warm. The coolant level is full(checked at radiator and overflow tank). Engine temperature is 193 degrees( checked with scanner). The heater control valve works properly. Any ideas....thanks. 2002 Insight.
 

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Which valve?

The flow control valve under the hood? (varies with temp knob)

Or the blend door inside the heater box? Actuator motor varies with heater knob & linkages actuate door.

Just a couple of ideas. And from your description the only two I can think of right now that are left! <g>

Please post back in this theread with the eventual fix too! :)

HTH! :)
 

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Discussion Starter #3
The flow control under the hood works. You can see the arm move from hot to cold as you adjust the temperature knob on the dash. I have not checked the blend door. I did however drive the car more today and found my engine temperature reaching as high as 221 degrees. I opened the bleed valve on top of the thermostat housing and some air came out
of the cooling system. However this made no difference. I am going to replace the thermostat and radiator cap as preventitive maintenance.
 

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Hmmm.

If ECT reached 221 then the heater should have been VERY hot!

Sounds like a coolant flow problem and it could be a stickey thermostat. Sometimes sticking open, sometimes closed. But with your earlier reply of ECT @ 193 and still no heat its sounding like a more serious flow problem of some type.

Save your money on the cap though. There very tough and none of your symptoms match a cap failure.

HTH! :)
 

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I opened the bleed valve on top of the thermostat housing and some air came out
There should be no air in the system, you don't mention if the coolant was just replaced, we would need some more information if we are to diagnose it the right way.

Here is what you should do, wait till the engines is cold, open up the bleed screw by the thermostat, until all the air is out, then try the heater.
 

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Additionally, "when cold" and after bleeding the air, replace with coolant mixture of 50/50.

How did you determine the ECT of 221?

Normal range is probably 204 Max.

Radiator fan will activate at 210 I think.

Outside air temp?

Need more info.
 

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Discussion Starter #7
The ECT was determined by connecting an OBD2 scanner. 221F was the
max. The range varied from 204 to 221. The coolant was flushed 7000 miles ago by a Honda shop. The ambient temperature was 50 degrees.
Thanks for the info on the radiator cap. My wife will pick up the thermostat today. I will bleed the system again(when cold). I do not recall the engine cooling fan coming on.
 

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Discussion Starter #8
By the way...why would air be in the system. The heater was working properly just days ago(30F) and my ECT was high 180 to low 190 temps.
 

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There's _always_ small pockets of air in the system. The air bleed on Hondas equipped with such is to prevent too much air from becoming trapped around the thermostat and effectively "insulating" it sufficiently such that it won't open when the remainder of the cooling system is overheating.

So a little "spit" of air can be normal.

HTH! :)
 

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Discussion Starter #10
Replaced thermostat today. No change in engine temps...seem to be normal. I have been paying close attention to the heat this week. It works sometimes and at times will blow cold air. No set pattern. This is some sort of intermittent problem...any more ideas....
 

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Hmmm,

Monitor ECT VERY closely. The earlier 221F is in the danger zone approaching the damage zone.

What concerns me most is some type of unusual overall flow problem. e.g. water pump impeller loose from its shaft which can cause a engine overheat damage. Further isolating the symptoms to: ECT remains in the normal range but heater operation is intermittent _should_ limit the failure to the heater only. And would have no consequences for engine damage.

Use touch (very carefully) to determine it the flow valve is actually opening in response to arm movement and allowing flow (mechanical failure of the valve). And any possible mechanical problems further back from this point. Inspect the Air mix motor and linkages for proper operation. Its the one of two on the heater box under the dash. And is on the passenger side bottom of the box.

Please let the group know as this problem resolves to a repair solution. :)

HTH! :)
 

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Discussion Starter #12
I disconnected the heater hose at the outlet of the heater control valve.
When operating the temperature knob on the dash the valve closes at the
coolest temperature and opens at the highest temperature. The valve works properly. All controls on the heater box under the dash work properly.
This weekend I will disconnect both heater hoses and attach a garden hose to check flow thru the heater core. I'm thinking the core may be blocked. I will report results this weekend. By the way the temperature gauge on the dash shows normal operating temperature. Thanks.
 

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Discussion Starter #13
Several days ago coolant was forced out of the coolant recovery tank. I refilled the coolant to the proper level and the heater works perfectly now. I may of had some sort of air pocket in the cooling system. I have no idea how this could have happpened. Thanks for all your help.
 
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