FAQ - About heater cores and hooking them up (WAS: The infamous heater problem)
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New User
Joined: Nov 2009
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From: Newport News, VA
FAQ - About heater cores and hooking them up (WAS: The infamous heater problem)
Ok guys, I've been searching all afternoon on here and can't get a good answer to my problem.
My 86 F250 5.0 EFI blows barely warm air out of the floor vents and defroster.
The blend door seems to be opening and closing fine. I can feel it when I move the lever. So I think that is fine.
The input hose to the heater core is hot and the output is fairly warm but I don't really feel much going through it.
The valve on the heater core moves and you can feel the valve open and close as well as the temp goes from cold air to kinda warmer air.
I did flush the heater core a month ago and it flowed very well.
I just dont know what to do or what to look for anymore. It just snowed 12inches and its cold.
Please please help.
My 86 F250 5.0 EFI blows barely warm air out of the floor vents and defroster.
The blend door seems to be opening and closing fine. I can feel it when I move the lever. So I think that is fine.
The input hose to the heater core is hot and the output is fairly warm but I don't really feel much going through it.
The valve on the heater core moves and you can feel the valve open and close as well as the temp goes from cold air to kinda warmer air.
I did flush the heater core a month ago and it flowed very well.
I just dont know what to do or what to look for anymore. It just snowed 12inches and its cold.
Please please help.
Elder User
Joined: Dec 2000
Posts: 570
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From: Austin Texas (area)
Is the correct T-Stat installed? Proper heater operation relies on the T-Stat. Usual recommendation is a 195° stat. Hose routing has a affect too. Hose from the T-Stat outlet should connect to the outside heater connection and the carb-side connection of the heater core should go to the water-pump.
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
If it is "barely blowing" but still cycles through the various speeds I would first remove the fan/motor unit in the engine bay and see if the squirrel cage fan is full of debris.
There may also be a bunch of leaves and stuff behind the heater core blocking airflow.
As has been discussed in recent threads your slotted cowl vent can be swapped for a 'polka dot' cowl from an '87->93 truck and that will keep a lot of leaves from making it in there in the first place.
There may also be a bunch of leaves and stuff behind the heater core blocking airflow.
As has been discussed in recent threads your slotted cowl vent can be swapped for a 'polka dot' cowl from an '87->93 truck and that will keep a lot of leaves from making it in there in the first place.
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New User
Joined: Nov 2009
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From: Newport News, VA
Thanks guys,
I'm not sure what thermostat I have in it, I bought it not that long ago and the guy never told me.
I'm sorry I wasn't a little clearer, I get ample air flow but the temperature is barely warm.
I'm thinking it has to be something with the heater core.
Are both hoses supposed to be the same temp? One will almost burn your hand and the other is just warm to the touch?
I'm not sure what thermostat I have in it, I bought it not that long ago and the guy never told me.
I'm sorry I wasn't a little clearer, I get ample air flow but the temperature is barely warm.
I'm thinking it has to be something with the heater core.
Are both hoses supposed to be the same temp? One will almost burn your hand and the other is just warm to the touch?
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
cold air. Perhaps a broken hinge or something. Open it up and take a look.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 39
From: EXTREME southwest CT
If one hose is hot and the other cold you have a clogged heater core.
You could try and flush it but a new one isn't much $ and you can be assured it's clear.
Either way you should remove the one in there.
If you are willing to chance it, try filling with some CLR or even white vinegar to loosen all the scale inside then back flush with a garden hose and reinstall.
You could try and flush it but a new one isn't much $ and you can be assured it's clear.
Either way you should remove the one in there.
If you are willing to chance it, try filling with some CLR or even white vinegar to loosen all the scale inside then back flush with a garden hose and reinstall.
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New User
Joined: Nov 2009
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From: Newport News, VA
Thanks everyone,
Ended up being, what looks like, 30 years of pine needles and leaves stuffed in front of the heater core. I took the blower fan off and reached inside and pulled it all out. A lot easier than taking off the whole assembly I think. Anyways, it blows pretty warm which is a HUGE improvement over the ice cold air I was getting.
At least I now know how the whole system works. Thanks for the happy ending.
Ended up being, what looks like, 30 years of pine needles and leaves stuffed in front of the heater core. I took the blower fan off and reached inside and pulled it all out. A lot easier than taking off the whole assembly I think. Anyways, it blows pretty warm which is a HUGE improvement over the ice cold air I was getting.
At least I now know how the whole system works. Thanks for the happy ending.
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Cargo Master
Joined: Dec 2004
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From: Florence, SC
Originally Posted by parr4
Hose routing has a affect too. Hose from the T-Stat outlet should connect to the outside heater connection and the carb-side connection of the heater core should go to the water-pump.
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Posting Guru
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From: Wagener, SC
Second....how does the slotted cowl come off? I looked in there as I'm also having heater issues, and it's full of pine needles. Do I have to remove the windshield molding to get to any bolts under it? I know I'll have to remove the wiper arms, but what else?
Post Fiend
Joined: Dec 2007
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From: Lost
I'm interested in that also.
Second....how does the slotted cowl come off? I looked in there as I'm also having heater issues, and it's full of pine needles. Do I have to remove the windshield molding to get to any bolts under it? I know I'll have to remove the wiper arms, but what else?
Second....how does the slotted cowl come off? I looked in there as I'm also having heater issues, and it's full of pine needles. Do I have to remove the windshield molding to get to any bolts under it? I know I'll have to remove the wiper arms, but what else?
Moderator
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From: Denver Metro Area, CO
with a Phillips screwdriver.
The radio antenna will keep you from totally removing the cowl but you'll have
enough room to tick your hand down there.
You might also remove the kick panels, crap tends to accumulate in there, too.
Elder User
Joined: Dec 2000
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From: Austin Texas (area)
Cargo Master
Joined: Dec 2004
Posts: 3,362
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From: Florence, SC
Thanks for the diagram, parr4.
According to that diagram, my heater hoses are indeed backwards, as my heater hoses are not crossed like the diagram shows; mine are completely parallel. Yet I still have good heat?
I wonder if anything "bad" would happen to the heater core or water pump if I reverse the hoses, after they have been "backwards" on my truck for the last three years? (When I rebuilt my motor 3 years ago, I couldn't remember which way the heater hoses routed, and parallel seemed to make the most sense to me.)
According to that diagram, my heater hoses are indeed backwards, as my heater hoses are not crossed like the diagram shows; mine are completely parallel. Yet I still have good heat?
I wonder if anything "bad" would happen to the heater core or water pump if I reverse the hoses, after they have been "backwards" on my truck for the last three years? (When I rebuilt my motor 3 years ago, I couldn't remember which way the heater hoses routed, and parallel seemed to make the most sense to me.)
