The heater fan switch has three contacts. 1 and 2 are connected at the first indent (Low) and contacts 1 and 3 are connected with the switch pulled all the way out.

Manual says:
" Two speed ranges are provided for the blower fan by means of a switch and a resistance unit mounted on the switch. Blower speed is reduced by the introduction of the resistance in series with the blower motor."

So far so good.
The only old remaining wire on the switch is connected to #3 and has an inline fuse.

Am I correct in running the wire to the fan motor to #1 and power to both #2 & #3?

My hesitancy is why wouldn't they have simply connected #2 & 3 in/at the switch itself? Why two separate wires both going to power?

Are we having fun yet?

 

Power would go in #3; goes from there to the external resistor and comes back in #2; goes out to the motor off #1. So you get direct power with it pulled all the way out, and it goes thru the resistor when pulled out to the first detent.

 

Ross,
Thanks, makes sense that the power would have been the one with an inline fuse...
But
Where does the wire from the fan go?

3 only connects to 1 (with the **** all the way out) but never connects to 2...
1 and 2 are connected at the first detent.

I'm confused (can you tell?) Two wires, Power and Fan, and three connections....

 

The resistor is across #2 and #3. With the **** pulled halfway out, power goes to 3, thru the resistor to 2, thru the switch contacts to 1.

Are you missing the resistor, or is it internal to the switch?

 

Well... that could be a curious development.... I made the assumption that the resistor was internal.... there is no external resistor... just the switch with three terminals.... 2 & 3 never seem to be connected. (according to my ohm meter)

Guess I could simply try "hot-wiring" it and see what cooks

 

Steve,

What you've got there is a switch for a two-speed fan motor. Ford used them quite frequently. A two-speed motor would also have two or possibly three wires depending on whether it has a separate ground wire or is grounded through the case. Power is wired to the switch on terminal 1 and terminals 2 and 3 are both connected to the motor on separate wires. When the switch energizes one wire, the motor runs on slow speed. When it switches power to the other wire, it energizes the other set of motor windings and runs fast. Keep in mind that the motor and switch you have may not be a matched pair.

 

BOR, you mean that the switch is not for the truck? It's a possibility since his quote from the manual says the resistor should be mounted right on the switch.

 

Well, I know something doesn't add up.... but everything else on the truck has been original... and there are only two wires on the fan motor, one going to ground on the firewall, the other running through the firewall to the switch.

Continues to be a mystery.

 

A couple of possibilities;

-- someone replaced the two-sp blower motor with a single speed
-- someone hooked up the blower motor leads wrong (both should go to the switch like BOR said, with internal grounding)

I looked up the switch on a couple of vendor sites. All of them say the 56 switch is 2-sp, none of them mention it for the 53-54, but the switches appear to be identical (see below). There appears to be room for a resistor inside the case, but I would think it would get hot as hell. Did you measure with an ohmmeter between terminals? (note how they are labelled on this picture, too -- B, H, L)

 

Ross,
I tried to find one on-line but couldn't..... my switch looks different.... the connectors are on the sides.... And there aren't any markings on mine.

My fan looks like the pix in the manual...

I did try "hot-wiring" but no matter how I hooked it up, the fan seemed to run at the same speed.... (albeit not very fast..?)

my daughter has my camera, but I will post a picture of the switch soon.

 

It is unlikely to have an internal resistor because:

• It would need to be ginormous to dissipate the heat
• It would only need 2 terminals, you have 3
• I have never in my electrical life heard of such a thing.

What I would do:

1. Disconnect wires from the switch.
2. With the switch pushed in, read between all 3 terminals with an ohmmeter. All readings should be open (infinity).
3. Pull the switch out to the first position, & repeat the readings. The resistance between 2 terminals (call them A & B) should 0 ohms (continuity) or nearly so. Other 2 readings should still be open.
4. Pull the switch all the way out. Repeat the readings. Resistance from either A or B to C should now be 0, other readings should be open.
5. If you do not get these results, the switch is likely history.
6. With the wires still disconnected, do what you normally have to do (switch on or motor running) to use the blower. Change the meter to read DC volts & check from all 3 wires to ground. Only 1 of them should show battery voltage - hopefully the 1 with the fuse.
7. Power down & connect the wire identified in Step 6 as the power to the terminal, A or B, that showed continuity to another terminal in both Steps 3 & 4.
8. Change the meter back to read resistance & read between the 2 disconnected wires. You should have some resistance value between the 2. If you do not, the resistor is likely burned out or missing. If there is resistance between the 2 wires, read from each in turn to ground while connecting & disconnecting the (non-grounded) wire from the motor. You should read an open with the wire disconnected.
9. Connect the 2 wires to the 2 remaining terminals & test run. If the motor runs fast on the first switch detent & slow when all the way out, reverse them.

I have seen pictures of trucks with what appears to be a load resistor on the firewall. If this is NOT an ignition ballast resistor, it MAY be for the blower.

 

Sorry - substitute "terminals" for "wires" in steps 2 & 3......

 

I had to take the switch assembly apart in my '53 to fix on it, and get it working again. The OEM switch for a one speed motor for the '53 looks like it has a big round cardboard looking tube with wire coiled thru it hanging off the back. There are 3 terminals on the switch, but only 2 places to connect wires to. terminals 2 and 3 look like they are connected together. The first position on the switch would send the current thru the card board tube coil of wires (the resistor) and then to the fan motor, for low speed. pull it out to the 2nd position and the current bypasses the cardboard tube resistor and goes to the motor for the "high" speed. That cardboard lookin tube gets hotter than sin and will burn the crap outta you if you try to touch it if the fan is running on slow. how or why it didn't start fires is amazing. What looks like cardboard is actually some sort of ceramic insulator I think. The standard "replacement" is an add on that clamped onto the bottom edge of the dash and had an internal resistor. That's the one i've most commonly seen in the catalogs listed as the replacement for the 53 & 54. They just left the original switch in the control panel not wired up. It too got hotter than sin when running the fan on Low. In my case, when I got the truck they had a 2 speed motor (replacement) hooked up with only the High wire to the replacement switch. I fixed the original switch and 86'd the nasty looking clamp on replacement. It's still clamped/hanging on my work bench shelf if any one wants the ugly lookin piece of crud.

I also had to take my blower motor apart to repair the wires as the insulation had all cracked off, but that's a whole nother adventure in fixing old trucks.