I was just wondering if anyone knew how to hook up the heater part only in an A/C.

The reason I ask is that the truck I am working on will be used as a farm truck, so I don't want to bother with the A/C. I do want the heater though.

Any help with this will be appreciated.

 

What exactly is taken apart?

You don't have to run the A/C to run the heater.

Josh

 

Well when I bought the truck none of the A/C or duct work is hooked up. The A/C is put together under the hood. I was just wondering what I takes to make the heater work.

None of the stuff under the dash that comes from the firewall is hooked up. I can try harder to clarify if someone still has questions.

 

So without any duct work you won't have defrosters. Your only heat option would be the floor. Find the proper duct work and install and the heater will work fine.

 

so under the dash is the heater and A/C separate from each other? Basically do they come in from the firewall in different spots?

Is the duct work for the defrosters different from the A/C duct work?

I figure that the heat only coming in through the floor would be good enough.

 

The heat and A/C come from the same box and are ditributed thru the same duct work. If all you want is floor heat that is what you will have currently.

 

So hooking up the heater only is pretty simple. Just get the duct work together and what else?

 

Do you have still have the controls installed above the radio? If so try to turn on the fan and make sure it still blows. If not then you're going to have to replace the blower too, or check to see if the wires are hooked up. And the cable that operates the blend door (that may not matter), and possibly the vacuum operated valve that is inline with the heater hose (also may not matter) but I have them both installed on my truck that is a factory A/C truck that the A/C isn't hooked up right now. I'm gathering parts to put the A/C back in there though.

 

The truck I bought was only partly put together. I have the head unit to the A/C but it's not hooked up. Honestly I don't even know how to get that together. I didn't know if their were any wiring diagrams or something along the same lines for the head units.

 

Does anyone know if their are wiring diagrams available for the A/C head unit?

Remember, I only want the heater part hooked up, so if there are any layouts for the duct work, that would be helpful also.

 

There are 3 things that have to work or have to be worked around...
1) get hot water to go through the heater core ;)
2) blower working
3) vacuum motors working (or wired into position) or all you'll have is
"defrost" since that's the "default" mode

The blower is on high when there's full voltage applied.
The blower's other speeds have a coiled-wire-resistor switched into
the circuit in series.

Do you need wire colors or what? :)
Got a volt/ohm meter? :)
We talkin'bout a 77 F150? :)
Do you have the metal dash out? :)
Were the plugs/connectors cut off or something? :/
The blower wires are heavier wires than most under the dash.
Oh yeah. :/
There's a relay involved with the blower motor with factory A/C.
Mine relay's went out a couple times, maybe that's all that's wrong?

Alvin in AZ
ps- my heater core control looks just like a ball valve... ;)
http://www.panix.com/~alvinj/file12/bypass.jpg

 

Y'all are assuming the OP's truck has factory A/C, but that may not be the case.

There were THREE different A/C systems used in these trucks.

If the A/C controls are in the same control panel as the heater, factory installed Integral A/C is present.

Integral means the heater/A/C ductwork, plenum chamber, and etc is the same.

Getting this setup to work without the A/C can be a challenge, because bolted behind the A/C/Heater control panel is this:

A/C Heater Vacuum Control Selector Valve Assy.

ALL the vacuum lines attach to this valve. When you move the lever on the control panel, this valve opens one damper door in the plenum chamber and closes another.

This valve also has the "kicker" switch on it, that activates the A/C.
------------------------------------------------------------------
If the A/C controls are in a separate location from the heater, there were two types of Ford dealer installed A/C, Deluxe & Economy.

The Deluxe A/C has separate controls, but the A/C and heater are an integral unit.

With this A/C, the huge dash bezel spans the entire right side of the dash, covering up the original glove box.

A separate glove box bolts to the bottom of the dash.
----------------------------------------------------
The Economy A/C is not integral with the heater.

 

First we are talking about an F-250 with factory A/C.

Second all the wiring is their, the wires are either capped off or removed when the PO started his resto.

The metal dash is in place. The A/C and heater was fully functional when the truck underwent the resto.

Since it was never finished, its all still unplugged. The heater core is still in place under the dash.

I would assume I can just plug everything back in to the head unit, and just not have cold air. Is that a correct assumption?

I just don't know how everything hooks up.

 

Sorry about giving myself a bump, I just need an answer.

Does anyone know where I can get wiring diagrams, or diagrams for the A/C duct work?

Do the ford part catalogs or manuals have this info?

 

The A/C wiring will be found in the FoMoCo wiring diagrams which were year and series specific.

Try helminc.com for a new original, or faxonautolit.com for a used one.

Parts catalogs have wiring diagrams, but they're really not worth a damn as far as tracing what wires go where.

Parts catalogs do show ALL the A/C parts.

You can buy a CD version of the 1973/79 Ford LIGHT Truck Parts Catalog from hipoparts.com.