1946 merc heater

oldskool

oldskool

Well-known member
have original working heater with 4 position switch,not installed yet,car is 12v I like the idea of reversing of the motor for defrost,will I have a problem running it on 12v besides fan turning faster ? anyone else running original 6v heater & switch ..thanks al
 
I run the same heater in my '40 that's converted to 12 volts.
The heater & switch (with bulb in switch) are 6volt & I use a resister I bought from Mac's,
part number--V12873.

Works for me.
 
Have same set up in my '47 which was converted to 12 volts. Uses a ceramic bodied resistor (voltage reducer). They can get fair hot and they recommend mounting them in well ventilated locations. Just be sure the resistor can handle the amperage draw.
 
I would not think the Sw cares if it is 6 V or 12 V. An easy way and cheap way to reduce the voltage is to go to a junk yard and get a blower resister from a 70's GM product. They are usually 3 speed so get your Volt Meter out apply voltage and find which terminal is close to 6 Volts. I used one for about 15 years for the heater in my 1951 F-1. Didn't change the Sw. But I did use a hole saw and made a hole in the bottom of the heater case and mounted the resister in the air stream to keep it cool.
 
Just my .o2: I had a '52 F1 PU. I used a genetic ceramic ignition resistor I had laying around placed in series with the original 6V heater switch (in the now 12V supply, +, feed wire), It worked the two speed 6V motor just fine for several years and was still working when I sold the truck.....Polarity did not seem to matter.
I don't have any specs, it worked with no problems so I left it in place....
RooDog
 

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Does anyone have a clear wiring diagram for the 46-8 heater and switch? This has come up before and always the only thing shown was a 40 or 41 diagram which is not the same. There are several wires to place so would like to do it right the first time.

I am getting a message from the "webpage" that says add three characters cause the msg is too short, never had that happen before.
 
jimTN said:
Does anyone have a clear wiring diagram for the 46-8 heater and switch? This has come up before and always the only thing shown was a 40 or 41 diagram which is not the same. There are several wires to place so would like to do it right the first time.

I am getting a message from the "webpage" that says add three characters cause the msg is too short, never had that happen before.
Click to expand...

Have a look at the 46-47 truck dash knob thread, it has a diagram of the 4 wire reversing heater switch.
Martin.
 
Long ago, before the internet, I decoded the arrangement myself on a junkyard '48 Ford heater and switch with shot wires and long-gone color coding. I sat down with the motor and a battery and puzzled and tested...I finally figgeredout that one pair of wires turned it one way, and another pair turned it the other. That was all I really needed, though it took me a long time to get that far...the resistors for low are built into the switch and the extra terminal just goes to the ignition switch. Figuring out my '49 Ford type 7-wire turn signal switch was MUCH harder...I mapped out all the terminals as hot or cold in all three positions, baffling myself in many new ways, and eventually had a eureka moment when I realized the the brake lead had to go off when the signal went on for each side. Fortunately, I was in college at the time, and classes afforded much time to think about important issues like this...
I'm sure my professors interpreted my wrinkled forehead and intense concentration on my notes as tribute to their wisdom.
 
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