Another heater question.

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Jan 30, 2018 | 05:53 PM

roadrash63

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From: nw pa.

Another heater question.

Hi I would like to know where the heater draws air from in the hot setting. 1985 F250 no AC
New new thermostat 195 new heater core.
New fan motor.
I cleaned the air box out and everything I could which was considerable do to mice.... With a Shop-Vac.
Low flow and temp is lower that i think is correct...
TIA

Jan 30, 2018 | 06:39 PM

Franklin2

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From: Virginia

It gets the air from the plenum at the windshield wiper area. Through the slotted grille between the hood and the windshield.

Jan 30, 2018 | 08:06 PM

cadunkle

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From: NJ

There is significant voltage drop to the blower motor through the factory wiring. Clean your switch and resistor, add a relay for the hot side along with upsized wiring. It will push more air once you fix the voltage drop.

Jan 30, 2018 | 09:27 PM

Tedster9

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From: Waterloo, Iowa

Maybe you know this already, check that both inlet and outlet hoses to heater core are HOT. If not, there is a restriction, most likely in heater core. Sediment rust or scale.

Jan 30, 2018 | 10:00 PM

ctubutis

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From: Denver Metro Area, CO

..........

Jan 31, 2018 | 05:19 AM

roadrash63

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From: nw pa.

Thanks

Thanks guys I will check it out I cleaned the plenum area with the Shop-Vac previously I have a new resistor also will check voltage

Jan 31, 2018 | 05:26 AM

roadrash63

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From: nw pa.

Heater

Hey I was just wondering if there is a mod or something . where you can reheat already warm cabin air instead of bringing in cold air and heating it cuz it's 13 here in Pennsylvania...

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Jan 31, 2018 | 07:10 AM

roadrash63

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From: nw pa.

Ok ty,
my blend door is wired to the hot position
On box in engine compartment !

Jan 31, 2018 | 10:43 PM

#10

kr98664

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Quote:

Originally Posted by Tedster9

Maybe you know this already, check that both inlet and outlet hoses to heater core are HOT. If not, there is a restriction, most likely in heater core. Sediment rust or scale.

Wouldn't you expect to see the heater outlet hose cooler than the inlet? That would indicate normal heat transfer into the cabin. I've never measured the temperature drop across the heater core, but on a radiator, you can expect to see the outlet hose about 30 degrees cooler than the inlet. I'd suspect a heater core to be similar, but don't really know.

Could the exterior fins on the heater core be plugged with debris? That would both limit the airflow and the heat transfer, since that crud can act as an insulator.

Try this quick test: With the engine off, turn the key to ON so the fan will run. Don't start the engine, so you can better listen to the fan speed. Set the fan on high, temp selector to full hot. If the blend door (temperature selector) travels properly, all air will be routed through the heater core. Next move the temperature selector to full cold. All air will now bypass the heater core. If the fins are plugged with debris, airflow will increase with full cold selected.