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Discussion Starter · #1 ·
Temp gauge shows normal (in the middle)
Output from engine to radiator is at 190 degrees at the thermostat housing.
in to the front heater core about 150, out at about 125.
Heater valve on the firewall is turning with the cable as it should.
Both the rear and front heaters blow lost of slightly warm air.
Engine does not overheat.
Would a failing water pump cause this?
Is there some likely spot that a hose from the engine to the heaters be plugged?
Is there another valve somewhere that I am missing.
 

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I haven't been into the cooling system deeper than the radiator and thermostat, but I'll take a swing.

I think you're on the right track - flow is restricted somewhere. If it was the water pump, pressure would be reduced throughout the system. Since the engine temp is normal, the problem is most likely in the heater loop.

Go back to fundamentals: burp the coolant to eliminate air bubbles as a problem. If no progress, see how fast you can feed water to the heater intake hose before it starts backing up. If you can confirm a restriction in the heater loop, you can test to isolate elements (hoses, core, valve) one at a time.
 

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Discussion Starter · #3 ·
back to this one again... On days over 50 degrees, heat from the front is warm. Not hot enough to force opening windows, but not too bad. Today, temperature has dropped to the 30's. No heat at all. Nothing else has changed. Worked yesterday, but not now when it's needed most. Is there anything that might cause this or is the Pilot haunted? It does not make sense that the outside temp can change anything. Even on recirc, no heat.
 

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Did you try burping the air out of the system as was suggested above?
When you change the temperature setting between hot and cold do you see the air mix doors move appropriately?
 

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Discussion Starter · #6 ·
all the doors move correctly. the air direction changes as it should. I parked the front end up on a big hill and burped the system. there is no sound of air bubbles. The valve is working as it should. I adjusted it to the valve is all the way to hot and then clamped the cable onto the valve. The rear heat does not work well at all, but that may need to be flushed. Haven't got to that as yet, but that should not affect the front heat, right? The valve is seeping a bit. Is that normal?
 

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When you burped the cooling system did you have both the front and rear heaters set for full hot? The front and rear blowers should have been off when you did that. You would not have heard air purging from the cooling system; you would have seen coolant bubbling from the radiator neck (cap removed). Process took me 20 minutes when it was 70 degrees outside. If it’s colder where you’re at it might take longer.
 

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And that valve at the firewall only controls heat to the front heater core. The rear heater core always gets full coolant flow.
 

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I recently posted this Accord Forum DIY fix. Confirmed to work by a fellow Piloteer @eshman99 .
See post #6 pics and video....
 

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Maybe not your main problem, but vacuum the rear blower for improved airflow.

142623
 

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Discussion Starter · #11 ·
thanks back at it in the AM. I have vacuumed the rear intake. It was clogged. Gonna try flushing again, all the hoses too.
 
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