Adding an EATC system to pre 1997 trucks
The first issue is control panel, the 1992-1996/7 trucks have an HVAC panel the same size as a lot of the EATC systems Ford used, earlier than 1992, say 1980-86 or even 1987-91, I can't say for sure, and the 1980-86 models had the fuel tank selector switch in the HVAC controls.
Second issue is the air flow in these trucks vs the newer trucks and most cars. The trucks use a face vent or floor defrost mode door and a no, partial or full defrost door, these are vacuum actuated. Later trucks and most cars use a upper or lower distribution mode door with a full upper, mix, and full lower position with a face or defrost door in the upper distribution. As a result most of the EATC systems are designed for this, giving you the bi-level features my 1994 Taurus has, floor/defrost and floor/dash in addition to full auto, max A/C, normal A/C, vent and defrost. Here is a picture of a 1996 truck heater case with the items mentioned identified.
The other problem, starting in 1995 Ford actually phased in the OBD-II systems on cars, with the OBD-II system, there is a twisted pair or communication wires that are used by various components to "talk" to each other in addition to allowing a fairly standard diagnostic tool to be used. When this rolled out, Ford redesigned the EATC controllers to use this network. One of the needed items on an EATC system is "cold engine lockout" so you are not blasted with ice cold air at full blower speed as soon as you start the vehicle, A/C demand will over ride this. All Ford EATC systems for vehicles with OBD-II capability do not have a separate CELO system, the EEC tells them "OK, heat now". My truck is converted to a an EEC-V which is OBD-II.
In prowling through a local junkyard, I found a 1999 Crown Victoria with this control panel.
You will notice the manual mode buttons match the truck **** or lever settings, with max A/C, normal A/C, vent, floor, floor defrost and defrost. I proceeded to remove it and the sensors and blend actuator.
Not knowing the exact location of the blower control module I couldn't locate it so have to go back and get it and the sunload sensor pigtail.
Set for max cool, actuator arm is fully (90°) CCW as viewed from bottom.
Set for max heat, actuator arm is fully (0°) CW as viewed from bottom.
Outside temp display (room temp).
Success! Now comes the fun, installing it. The easiest way is going to be to remove the dash to run the wires neatly. I will probably do that and run all the wiring, add the tube for the in-car sensor and the needed holes for sunload and in-car sensors. Fortunately, even using the 1996 harnesses, since the truck and donor truck are both > 8500 GVWR, there are no air bag wires so I have a number of empty pins in the main bulkhead connector, C202 for the ambient sensor wires and if needed the 3 small wires for the blower motor speed controller which goes underhood on the 1999 Crown Victoria.
Outside portion.
[I]Connector, two large pins are blower motor negative and ground.[/I
Items that need to be added consist of:
1 - Ambient temperature sensor, mounts in front of condensor
2 - In-car temperature sensor, on Crown Vic, has a small grille in dash
3 - Sunload sensor, needs a hole in the dash facing up
4 - Blower motor speed controller, on Crown Vic, is on inboard side of underhood case
5 - Blend door actuator, on Crown Vic mounts on top of heater casing
7 - Aspirator hose air source, needs to come from system underhood case, or at least upstream of blend door
8 - Wiring, I have enough pieces for the various components, but they need to be connected to the components.
9 - Control head, should bolt right in
10 - Power sources, 3, one always on and two on in run.
11 - Vacuum harness, hopefully the in-line connection is the same on both vehicles so that will be simple
Wiring discussion:
Item 1 needs two wires, a light blue with orange and a pink with black run from the front of the truck, through the firewall to the control head. Item 4 needs a location, then wiring run through the firewall to the control head and a suitable ground. Item 2 needs a location, then two wires run from it's location to the control head, a white with orange and a pink with black. Item 3 needs a location and two wires run from there to the control head, a brown and a pink with black. Item 4 needs a location and a total of 5 wires, 3 of which go to the control head, one to the blower motor and one to a good ground. Item 9 needs it's connector plugs installed, and in addition to the previously mentioned wiring, needs, for my truck and any other OBD-II truck, the two wire twisted pair for the multiplex communication network tied into the existing pair. Item 5 needs it's 5 wires run from where it will be mounted to the control head location. I am somewhat **** about my wiring, no crimps, everything soldered and heat shrink tubing used over it and I prefer to make it as neat as possible by running it along and taping it to the factory harnesses. I also prefer to use the factory bulkhead connectors. This means the dash has to come out in order to run the majority of the wires. This will also help in the installation of the sunload sensor, in-car sensor and blend door actuator.
What I will probably do is once locations have been determined, including the blend door actuator, I will remove the dash and do all the wiring additions, but not necessarily install the system at that time.
I did verify that the vacuum harness connectors are the same so that that part becomes easy.
Vacuum harness connector and shallow recess for module.
Other item, I verified the rotation direction on the blend door actuator, it moves 90° degrees at the lever and looks like if I can mount it to the main part of the case it will not interfere with a heater care replacement.
Inside case with temperature control cables (late style) attached.
These are a bit hard to see, but the pink colored piece is the blend door lever, in full heat it is parallel to the firewall, in full cold it is perpendicular in a 90° rotation clockwise viewed from above. Actuator has the same position and rotation.
Blend door in full heat position.
Blend door in full cold position.
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Full cold position.
Full hot position.
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Now, when I have time to pull the dash out I will run the inside wiring and install the control head which due to the shallow depth of the area is going to have to be in two pieces.
Remote mounting the four solenoids won't be too hard once you identify the power/signal wires for each one. If you have a sketchy one, you might even consider different solenoids entirely as I did with my RX7s twin turbo control system. As long as you can get the vacuum lines connected, who cares where they came from
The included picture may give you some ideas, look in the bottom left corner to see my solenoid rack for the twin turbos..As for the control box, here's a simple idea: cut a section out of the middle, then glue/weld/etc the front and rear pieces back together. Look for a polymer ID on the box so you can properly mate the halves back together
My goto connectors are Delphi Metripack 150 sealed connectors, but they are limited to 10 pins max. But since you're handy with a soldering iron, check out Tyco Electronics (now TE Connectivity) Superseal 1.0. Haltech ECUs use them, as do several Chrysler minivans. The PCB ones can be soldered onto jumper wires with some finesse, while the harness side ones are crimped. They come in 26, 34 and 26+34 pin versions.
FWIW, I rewired the entire truck from the original 1986 system to a 1996 system and changed the dash and interior to a 1996 system. Go through some of my other threads, truck now has automatic headlights and a few other not originally offered options.







