A/C & Heater Wiring

Hello Guys,

i got a big problem to connect the wires of the A/C & Heater the right way.

My car is an 1966 dodge coronet with an ron francis wiring harness. 2 Years ago i deleted the heater because it was leaking, now i rebuild it and want to get it all back in the car. Everthing works perfect (replace the heater core, replace the seals in the box etc.), but the wiring of all the stuff is really hard for me.

My harness has 1 brown cable (called "heater", and the instruction manual says it should go to the heater switch for power feed). The 2 cables on the blower motor are green and black (i suppose black is "ground"), but where i have to put the green cable on?

I don´t know which cable is going to which connection...

Here are some pictures:

my heater blower switch in dash has 3 connections:


the resistor for the blower motor on the heater box has 6 connections:


...i think connection 4 & 5 are for this connector:

but the other connections i dont know.

my vacuum switch (which is in the dashboard) has the following connections:



Maybe somebody could help me out...i don´t understand the wiring in my shop manual because of my aftermarket harness and i can´t find something which helps me with the connections in the forum search or the internet. I only want to get the heater working, the A/C is still deleted...i don´t need it here.

Thanks & kind regards from germany

max

Hiya, Max.

Should I guess the color coding on the wires are different? That's usually how you tell what goes where.

Otherwise, only thing I can think of, is to backtrack your wires, going by your service manual wiring diagrams. For each wire, trace it back to the hookup at the other end, using that as a guide for the ends you need to hookup.

Hi miller,

my problem is that i only had the Ron Francis wiring, all original wires are gone.

Here is an scan from my original wiring:


I would connect it the following way:

C1A: not connected
C1B: not connected
C2: not conneted (i dont have an "temperature control switch")
C2A: not connected (i dont have an "temperature control switch")

C4A: rewire a new brown cable to the resistor

C5A & C5B: these two got the same connection on the blower switch

C5A: rewire a new dark green cable to the resistor
C5B: rewire a new dark green cable to the blower motor (trough the firewall)



C6A: rewire a new light green cable to the resistor

C7: rewire a new tan cable to the resistor

C8 & C9: take the connector which comes from "A/C and Heater resistor bypass switch" and just plug it in (this cable is still existing)


But the question now is where i had to connect my brown "Heater" cable (power feed from fusebox) from my Ron Francis harness?
And did the heater work without the connections C1-C2? (i don´t know what this connections do)?

mmmaaaxxx said:

But the question now is where i had to connect my brown "Heater" cable (power feed from fusebox) from my Ron Francis harness?
And did the heater work without the connections C1-C2? (i don´t know what this connections do)?

Click to expand...

No electrical genius (just get by), but on the first question, are you saying the wire color is different? Only suggestion is to go by wire size, if color is wrong. Hot lead wires from fuseblock should be fairly easy, if everything else is hooked-up.
But, you say no temperator control switch? Just looking, I'd guess it's needed.

C1 and C2 leads (in the diagram) are your hot leads. So, again not sure on the 'brown' wire. Two browns showing, both going to resistor. Only working two wire sizes, 16 and 18, which will give some clues.
Black with tracer, and light green shown as hot leads from fuseblock.

C2 wire could be also for the heater's air doors, that control how much air passes through.
Just guessing, the temp control switch has two positions, high and low. that's where the airbox doors come in, setting how much they open.

Well? Does it work?

Off the top of my head, C2 normally feeds the AC compressor clutch.

Brown "Feeder" for heater on new harness should go to a fuse and a switch and then to C4A. This is ASSUMING that you will not be using the original AC controls.

Note that the switch (on the box) that goes to C8 and C9 simply causes the blower motor to run faster by shorting out the 0.2 Ohm (sown as being to the far left) resistor wire. This switch is only closed when the proper ("AC"?) door is open on the box. That will happen only when there is vacuum to the "rear" port of the longest vacuum actuator can.

See AC Diagnosis for 1969 model year at mymopar.com: http://www.mymopar.com/index.php?pid=446

Enjoy! :glasses10:

Cut/paste from another post, related info:
You can test to see if all three of your resistors are good, they should measure 0.2, 0.4 and 0.8 Ohms (plus any meter lead resistance). They look like coils of wire. The unit probably has a switch on the right near the vacuum cans. It is a bypass switch. This switch shorts out the 0.2 Ohm resistor when one of the linkages is in the right position.

BTW: MyMopar reference section has a description in 1969 AC Controls section. The PDF page 12 zeroes in on the blower controls and resistor.
See: http://www.mymopar.com/index.php?pid=446

By the way: The 1967 service manual, and perhaps some others, appears to be drawn badly wrong in the specific area of the blower switch and resistor.

Thank you all.

I still don´t have all parts for the heater box (i am waiting for the heater by-pass valve...without that valve i can´t connect my heater core with the firewall outlet). As soon as the valve is here i will build all in the car again and let you know if it all works properly.