HVAC Systems
Illustrations and part numbers for the heaters and air conditioning systems for the Bullnose (1980 - 86) Ford trucks.
Over the years Ford had three different Heating, Ventilation, & Air Conditioning (HVAC) systems from the factory, and then there were variations within them. They were the base heater, then the Comfort Vent or Deluxe system, and finally the Integral A/C system.
If you didn't order an optional system from the factory you got the "standard heater".
The first upgrade above the standard heater was the Comfort Vent system, which was also called the Deluxe heater or Hi/Lo because it had outlets in the dash for the Vent position.
Integral A/C was what Ford called their factory-delivered A/C system. They did have dealer-installed A/C systems, but those varied a bit as the dealers could install whatever they wanted. But from the factory is was "Integral A/C".
Below is the main plenum assembly (18471) as well as the floor duct (18C433).
Below is the right side duct (18B680).
Below is the left side duct (18B680).
Below is the defroster duct (18490).
Back side of the dash with the left and right ducts attached.
And here are some pics of the underhood housings:
Here's a pic of the vacuum hoses along with their part numbers:
This is the high output heater core with part number E0TZ-18476-A, which was replaced by E3TZ-18476-F. Note the insulation around it.
There are really only two different HVAC controls, although there are several variations on them depending on whether the truck had dual tanks, electric fuel pumps, or was a Bronco with a rear window switch. But basically there are the early controls, from 1980 through 1982, and the later controls for 1983 through 1986. Here are several pictures of the two:
Sometimes people want to swap one control for the other. And while they will bolt into the same opening there are several differences in their "connections" that require a bit of effort to make the swap work. Specifically:
- Heat Cable: This is the one un-answered question. So, if we can answer this one I think we will have this nailed.
- Vacuum: There's a vacuum harness for each of the controls, meaning early vs late, and you have to use the correct harness. But, the vacuum motors didn't change, so use the harness for the control you have.
- Blower Motor: The blower speed switch was the same from 1980 through at least 1989, so this connection is not an issue
- Tank Selector: There were several different switches, but they will swap from the early control to the later control and vice versa. So, this isn't a problem if you have both controls available.
- Illumination: The connector for the bulb to illuminate the control is different from the early to late control. But, the socket, wire, and connector can be easily swapped from one control to the other.
- Function Switch: The connector on this switch went from a square plug to a flat plug, but both have the same 4 wires. So Jonathan/Ford F834 has figured out how to pull the pins out of one connector and put them in the other, so this one isn't a problem either - once he writes up his how-to.
See the picture of the hoses and their PNs on the Illustrations, Pics, Etc tab, then the Integral A/C tab, and then the Pictures tab.
One problem the Bullnose trucks have is that the engine coolant is always circulating through the heater core. Even when the doors in the HVAC system are closing properly there is some heat coming into the system. In fact, that makes the air coming into the cab on Vent much warmer than the outside air. And, it makes the air temp when the A/C is on much warmer than it could be.
Fortunately there's a fairly easy fix for that - install a valve in the heater hose and shut off the water when not needed. And there are at least four ways to do that:
Fortunately there's a fairly easy fix for that - install a valve in the heater hose and shut off the water when not needed. And there are at least four ways to do that:
- Manual shutoff valve - and remember to shut the flow off when it is warm out or turn it on when it is cool out.
- Electric-operated water valve and rig a switch somewhere.
- Vacuum-operated water valve tied to the Recirculate hose under the hood. But this only works when in Max A/C, which is the only time the Recirculate door is closed.
- Electric-operated vacuum valve and vacuum-operated water valve
- Vacuum-operated water valve tied into the HVAC controls such that the valve is shut in Vent and Max A/C.
My favorite approach, although I've not actually installed the valve yet, works without any thought required from the operator. However, it only works on trucks with the 1980 - 82 HVAC controls as the 1983 - 86 controls can't be easily modified for this use. But, you can swap the earlier controls into a later truck, as explained on the Swapping Controls tab above.
As for how to implement the modification using the earlier controls, you will need a vacuum operated shutoff valve, a length of 1/8" vacuum hose, hose clamps, and a 2" piece of 1/8" ID brass tubing. For the vacuum valve there are two slightly different approaches: a 2-port or a 4-port valve. On engines with a bypass system, which is most if not all of the engines used in these trucks, a 2-port valve should be adequate as the bypass system will circulate coolant in the engine while the valve is shut. However, some people are using the coolant in the heater hoses to heat the carburetor, and in those cases a 4-port valve will be needed.
As for how to implement the modification using the earlier controls, you will need a vacuum operated shutoff valve, a length of 1/8" vacuum hose, hose clamps, and a 2" piece of 1/8" ID brass tubing. For the vacuum valve there are two slightly different approaches: a 2-port or a 4-port valve. On engines with a bypass system, which is most if not all of the engines used in these trucks, a 2-port valve should be adequate as the bypass system will circulate coolant in the engine while the valve is shut. However, some people are using the coolant in the heater hoses to heat the carburetor, and in those cases a 4-port valve will be needed.
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For a 2-port valve Four Season's 74612 will work nicely as it it has ports that are arranged so it can be supported by the heater hoses, as shown to the right. (The Four Seasons 74614, which is for an 84 or 85 Tempo or Topaz and should be the equivalent of an E4FZ 18495-A, is a normally-closed valve and opens with vacuum, which is exactly the opposite of what you want.)
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But , pretty much any other valve that closes with vacuum and has 5/8" water ports will work well. Or, if you want a 4-port valve to loop the coolant back to the engine while the valve is closed there's the Four Seasons 74776 or Four Seasons 74809 or NAPA PN BK6601294
The vacuum control for the 1980 - 82 trucks works as shown below, which is taken from the 1981 shop manual. Note that Port 1 isn't used, but that it gets vacuum from the source, Port 7, in both Vent and A/C Max. Perfect!
The vacuum control for the 1980 - 82 trucks works as shown below, which is taken from the 1981 shop manual. Note that Port 1 isn't used, but that it gets vacuum from the source, Port 7, in both Vent and A/C Max. Perfect!
The ports are shown on the left, below, but you don't actually hook your vacuum hose up to the nipple labeled as "1". Instead, there's connector, shown in the middle picture, that pushes onto the ports and clips on. But, Port 1 doesn't have a hose connected to it. So, the trick is to drill the connector and push the piece of brass or plastic tubing in, as suggested with the red lines in the picture on the right, below. But, I would use some kind of sealer on the tubing as you press it in to ensure you don't have a vacuum leak. Then, connect your vacuum hose to the tubing, run it through the firewall, and connect it to your valve that has been installed in the heater hoses. Problem solved!
In the three bottom pictures I've drilled the connector and pushed a piece of plastic tubing, that I found on the HVAC system of a 1990 truck, in and sealed it with red Loctite. Then I'll connect the 1/8" vacuum hose to that and run it through the firewall to the shutoff valve.
In the three bottom pictures I've drilled the connector and pushed a piece of plastic tubing, that I found on the HVAC system of a 1990 truck, in and sealed it with red Loctite. Then I'll connect the 1/8" vacuum hose to that and run it through the firewall to the shutoff valve.
