Heater core
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Grumpy goat
Joined: May 2017
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Heater core
Would someone please post engine compartment pics of a '79 F150, with no A/C?
The truck I'm "restoring" had the heater core disconnected. I'm guessing it was leaking. I know how the hoses should be routed. I'm gonna test the core for leaks, though I'll replace it either way. But I need to see if anything is missing, like the valve that controls the amount of water running to the core. I don't know if it's inside, or if it's outside and no longer there.
BTW, I have the previous owner's Haynes manual. He obviously owned a yellow highlighter pen. I feel like a detective, thumbing through the book. I find his highlighted areas, then go check the truck. Heater core and blower motor are highlighted.
The truck I'm "restoring" had the heater core disconnected. I'm guessing it was leaking. I know how the hoses should be routed. I'm gonna test the core for leaks, though I'll replace it either way. But I need to see if anything is missing, like the valve that controls the amount of water running to the core. I don't know if it's inside, or if it's outside and no longer there.
BTW, I have the previous owner's Haynes manual. He obviously owned a yellow highlighter pen. I feel like a detective, thumbing through the book. I find his highlighted areas, then go check the truck. Heater core and blower motor are highlighted.
Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 49
From: Great American SouthWest
The high-output heater does not have a water valve in the engine compartment. Also, the high output has a larger diameter hose
I think only the factory air vehicles had a valve in the heater hose.
I think only the factory air vehicles had a valve in the heater hose.
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Grumpy goat
Joined: May 2017
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Yep, you're correct (Duh, like you needed me to say that). It all looks pretty straight forward under the dash. So now there's the task of pulling the dash, replacing the core, checking switches, cleaning plenums, etc. I'll probably pre-order the fan switch and any other stuff that looks perishable. I hot wired the blower motor and it works well. Thanks again, Papa
Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 49
From: Great American SouthWest
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Grumpy goat
Joined: May 2017
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Papa, correct me if I'm wrong. The heater control valve I see in diagrams and pics is a vacuum type. Since a lot of the vacuum lines were gone from this truck when I adopted it, and I've trimmed vacuum down even more by installing Edelbrock manifold and carb, I'll need to put a vacuum port fitting in the manifold, and run a hose to the heater valve. Correct? The manifold has an unused vacuum port in the left rear that I've plugged. Seems logical that'd be where to tap heater valve vacuum from
Cargo Master
Joined: Nov 2011
Posts: 3,354
Likes: 49
From: Great American SouthWest
Papa, correct me if I'm wrong. The heater control valve I see in diagrams and pics is a vacuum type. Since a lot of the vacuum lines were gone from this truck when I adopted it, and I've trimmed vacuum down even more by installing Edelbrock manifold and carb, I'll need to put a vacuum port fitting in the manifold, and run a hose to the heater valve. Correct? The manifold has an unused vacuum port in the left rear that I've plugged. Seems logical that'd be where to tap heater valve vacuum from
If you don't have factory a/c, you may not have an under-hood water valve. With the high-output heater, the water runs through the core all the time, but a blend door controls air-flow over the heater core. I think the blend door is cable operated.
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Grumpy goat
Joined: May 2017
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Yeah, as far as I can tell, without tearing into it, water circulates through the core all the time. That's probably why it was disconnected. Lotsa heat in the cab. If that's the case, when I re-do this thing, I'll probably put a H valve under the hood. For summer driving, I can manually turn the water back around before it reaches the core.
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Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Dealer installed A/C or w/heater only does not have this valve which has been a notorious POS since day one!
It's been a "best seller" since 1971, so it's still available from Ford. It's notorious for getting stuck in the open or closed position or between both positions.
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Laughing Gas
Joined: Mar 2015
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From: Pittsburgh
I'm not sure where you live, but I have heat only with coolant running through the heater core at all times. I don't think it adds any heat to the cab in the summer as long as you don't have it turned on and you have the blend door shut.
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