i apologize in advance if this question has been asked before...i tried a search, and didn't have much luck...as i'm now in NorCal for the winter... i am beginning to acutely feel the fact that my heater doesn't really work at all that well (not so important when i tended to try to stay where it never got colder than 40 LOL).

hot air DOES come out the vents/defroster if i have the heater/defroster on, but there's no force behind it.. like the fan is on, but barely working at all (enough to partially defrost/defog the windshield OR warm my feet, but typically not both at the same time, and either of those only after the truck is well warmed up)... if i shut off the heat, all airflow stops completely (and my feet get cold. LOL). also, when i first start the truck on a cold day, if i left the heater on from my last trip, it begins to make the most godawful howling/whining noise until i shut the heater off. once the truck is warmed up a bit it doesn't howl/whine.

i'd like to know what parts to look at/take out/rip apart before me and my husband get elbows deep into the project, as currently the truck is our only vehicle.

1978 F-250 camper special 460 with factory air. (which doesn't work either, but screw it. that's what opening the windows is for!)

 

Here is a link to a post that has links to several different write ups. I just replaced my heater core, in fact finished it up this morning. It is a bit of a pain, so i would replace both the blower motor and heater core while you are in there. Might also need to replace the valve in the engine compartment. It is for shutting off the coolant to the heater core when the air is on, and often corrodes. Good luck.

https://www.ford-trucks.com/forums/1...wer-motor.html

 

You could try putting a 12 volt wire on the positive post of the blower motor and see if the blower motor/fan turns on to high speed.
If it does, then you could have a bad fan speed switch, or maybe the solenoid.

Unk Bob

 

Like most blowers, this has a resistor pack, and high is straight voltage. This usually means if it goes bad, you only have high. Since it makes a racket when cold, most likely the blower is needing replaced.

 

And to add to the contemplation (lol) does it smell like somethings getting hot that shouldn't be (like that stink bakelite makes when it gets hot)?

Our blower runs on only one speed and man does it begin to stink after a few minutes.

Northern California has gotta be (besides being sub-40 degree climate) one beautiful place to be during the Winter!

Looking forward to hearing what y'all find and how you fix it.

 

no funny smells. i had a heater core go bad in my '85 ranger i had as a kid... i remember well what that smelled like. just the lack of air flow/fan noise, and the howl when cold.

 

Concur with the posts above regarding coolant flow and potential issues with the valve or core itself.

I'd verify that the controls are actuating the doors fully closed or open depending on the settings. Sometimes the cables are not indexed correctly so the valve or door may only be partially open. Hence, the tepid temperatures that are experienced.

The other potential issues is with the seals inside the heater box... they're made of foam and degrade/crumble over time so it might be time to crack it open and replace them so the doors seal against the flange or case.

.

 

Lack of airflow could also mean things are plugged up. Debris getting into the cowl could be making its way down into the box blocking airflow through the core.

 

when i have a day off that isn't also 9 degrees i'll dig around and see what i can find.

 

Welcome to the forums and the 79s. Grew up with these trucks we had one since, well long before my time. If you have the ac cab, the heater works fair. If the non ac cab, just heat and vent, not much there at all. Yours might be plugged somewhere. There is a few things to look at, there is a door for fresh air or "off" above the passenger floor board, it might be worth shining a light in there and seeing if anything is living there, if it ain't paying rent, its gotta go. you can see theevaporator there, look at the top cowl, and look and see if pack rats built a nest down in there, stopping the air intake with leaves and such.

 

It can be plugged up in the cowl, plugged up in the box itself, or plugged right on the heater core - years of airflow across that core will accumulate a lot of stuff like lint, etc. and seal them off nice.

BUT - if your fan howls at certain times, I'd be almost 100% positive it isn't running full speed even when it isn't shrieking. You need a new fan motor, or at least need to take it apart and clean/lube it. And as long as you have it out, if it's heat only, another 6 or so screws and you can clean up the heater core.

 

From the video it looks like you have the factory AC system. You definitely need to replace the fan motor and I would highly recommend that if you do it you also replace the heater core. Some extras items that might be worth changing are the coolant heater valve and thermostat.

Here is a very good write up on how to do the core and motor replacement on a truck with factory AC.
NORTH COUNTRY SPECIALTIES ®

 

+1 what Orangeford said, also replace the relay. My defrost wouldnt work but I could hear the door open when switched. I took a drain snake and worked it down the defrost vents and pulled up a mouse nest of OEM fiber floor insulation. My defroster works great now!!

 

Your blower motor sounds a lot like mine did. It is moribund. Mine died weeks after making that sounds. Seized up. A new, $18 motor was a fairly simple fix and works MUCH better.

 

I agree, the motor sounds like the bearings are shot. It needs a new motor.

If the truck is a keeper and the heater core age is old, or unknown, might as well replace both.

If you just wanted to replace the motor, there is a thread or two, about replacing it from the engine compartment.