Okay-one step at a time. I am fixing problems as I encounter them, but as winter is nearing, I'd like to get the heat working. Where do I start? I have a 1976 F-100 with a 390 in it. It seems the last owner cut all "unnecessary" luxuries in the engine. There is even a belt missing which used to drive some of the pulleys (smog pump--I think, and it's seized, and one other--not sure, but truck runs without them.
Sorry if I seem ignorant--I used to work on older cars a lot, but it's been about 10 years. I'm relearning as I go.

Where do I start when it comes to heat? Thanks for any knowledge in advance, everyone has been extremely helpful with all of my questions.

 

You gotta start with some fire in the wire and hot water in the heater core!I hope this gives you a step in the rite direction.

 

First, do you have factory a/c? If you do, there is a "big box" under the hood on the passenger side that's bolted to the firewall.
Second, are the heater hoses hooked up?
Third, does the blower work?

 

Then after you figure out the answers to the question Mike asked you, and if you can't go to the local auto parts store and buy you a $12.00 Chilton or Hays auto repair manual for your truck.

Ck fuses and dash duct work and vacuum actuated valves, maybe you have one inline with your heater hoses?

Then a get and do radiator/block flush, get the kit so you can do it more than once. Usually the inside of these ol blocks are nasty.

Ck the thermostate to see if it is working with the pan of hot water trick (google it). Hopefully you do not need a heater core replaced. PITA

You only need a alternator and p/s belt.....you are not "ignorant" you are relearning some forgotten information, that's what the suggestion to go get the book is for.

 

Factory installed Integral A/C is combined with the heater. The A/C controls are located in the same panel as the heater controls.

With factory A/C only: There is a vacuum controlled heater water valve spliced into the inlet-to-heater-core heater hose.

It's a notorious POS! Gets stuck partially or fully closed, so little to no water can pass thru it to the heater core.

D4AZ-18495-A (replaced D1AZ-18495-A) .. Heater Water Valve -Use with factory installed Integral A/C (Motorcraft YG-136) / Available from Ford.
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1975/79 with factory A/C: D5TZ-19B888-A .. A/C/Heater Vacuum Controlled Selector Valve Assy. Located on the backside of the A/C/Heater control panel.

All the vacuum lines connect to it, then to the blend door motors and POS heater water valve. When you move the lever on the A/C/Heater control panel, this valve opens one blend door, closes another.
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1973/79 with factory AC: There are THREE different blend door vacuum motors. Failure of motor of whatever door it controls (won't open...or close), causes chaos with the system.

D3TZ-18A318-A .. A/C/Heat Door (Motorcraft YH-219) / D3TZ-18A318-B .. Heat/Defroster Door (Motorcraft YH-218) / D7TZ-18A318-A .. Fresh Air/Recirculating Door (Motorcraft YH-308).

When factory A/C works correctly, that's just ducky. But if it doesn't work, figuring out what's wrong with the complicated turd is a PITA.

 

Below is a great picture of a late model Dent with 351m/400 and AC that I saved for "inspiration" someday. You see the heater hoses and a vacume controled valve. The valve is activated by the controls, for strictly winter use you could substitute a manual valve or if cold enough for long .... eliminate it.

You also need to be sure your heater core is "sound" .... if someone removed the heater hoses before. If not so good, you'll know real fast. You could use 2 short pieces of heater hose in a loop between the two core fittings and short piece of copper tube same size, 4 clamps, and sweat solder a shrader valve fitting and maybe fitting for small air press gage in the copper tube. Use a hand pump only and pressure test at no more than 16-17 psi and see if it holds?

Once you get that done, check to see if blower works, check fuses if not. Might need a switch?

You do not need the AC or AC compressor hooked up to get heat or defrost or defogging, and back then the AC was NOT used with defroster vents though now-a-days it's common (and so I wired a switch to cycle my compressor for fast defogging (AC will dry the air) if desired).

 

Really? Is factory "all black" and plastic or is that the "part metal / part plastic" one I wonder?
I am glad it's available, but I must say mine has never shown a sign of problem and it's been there since I installed factory integrated AC from 2 donar trucks in 1987 .... though I did use a new heater controla valve then. I have replaced hoses since then however.
Mine is "all black" like below and some kind of plastic (likely NAPA), but it seems to work still.

 

If you were a Ford partsman, you would know: It's a POS and has been since first introduced in 1971 Passenger Cars as D1AZ-18495-A since replaced by D4AZ-18495-A

Besides misc 1971/86 Passenger Cars, 1973/79 F100/350's & 1978/79 Bronco's wth factory A/C, the little charmer was also used in 1975/2007 Econolines and etc etc etc.

MSRP: $34.46 // FTE sponsor tousleyfordparts.com price: $18.95 / There are 879 applications for the little charmer listed on Tousley's website from 1984 thru 2007. Whiz over there, take a look-see.

Tousley Ford ~ White Bear Lake MN / Website: Click on HOME, then type the part number into the "Search by Part Number" box, then click on Ford and sit back and gaze at the 80 pages of applications.

 

About a year or so ago someone posted a problem with their factory a/c heat combination, they were a little confused and I don't blame them.
It turns out a PO (and we all know how bad they can be) had a leaking heater core. Instead of replacing the heater core, they disconected the a/c lines at the evaporator and hooked up the heater hoses to the evaporator.
I will give the PO points for originality and thinking outside the box .

 

Hah