'63 Heater switch

[Gary Cederman]

First off, I have no history of how the heater worked because I have only been rebuilding my '63 since I have owned it.

I am testing the heater switch prior to installing it and noticed that of the three ON positions of the switch, the third position has both the 2nd position wire post and third position wire post connected to the center wire post. (Hope that is not too confusing.) What I was anticipating to happen was that each wire post would match each switch position one-for-one with respect to connecting to the center wire post (a SPTT switch). That only happened for the first and second positions. But, as I just stated, for the third position, the center wire post is connected to both the 2nd position wire post and third position wire post.

Drawing out the circuit and including the heater resistors (two resistors in series with a center tap) and the heater motor. It appears that what I stated above gives me both a connection from 12 volts (due to the 3rd position wire post) and directly to the motor and a connection via one of the resistors from 12 volts to the motor. This appears to just short out the resistor circuit. So, I thought that maybe the switch is bad (or dirty) OR maybe I am over looking something.

Can someone tell me if the switch should be a one-to-one with the center tap or what I described that my switch is doing is correct?

Thanks,

Gary

[Duke W.]

Re: '63 Heater switch

I think it works like this. The fan has three speeds. The max speed provides full system voltage to the blower motor. The middle speed cuts the voltage with one series resistor and the low speed adds the second series resistor to further cut the voltage to the motor.

You can probably test this by attaching the connectors to the switch and resistor assembly, then measure for resistance between the motor connector and the 12 V source on the switch - should be zero at high speed, some resistance at the middle position, and greater resistance at the low speed setting.

The wiring diagram in the Shop manual isn't too much help, because it doesn't show the schematic details of the resistor assembly or the switch.

Duke

Duke

[Gary Cederman]

Re: '63 Heater switch

Duke,

The circuit you have described is what I thought it should be. That is part of what I was trying to say in my post. The problem is that when the switch is in the high position, (i.e., the resistors are out of the circuit) the 2nd and 3rd tabs on the switch are both connected to the center tab of the switch (which is tied to 12 volts).

I think that my assumption is correct that it should only be a one-to-one connection for each position of the switch! (Low = two resistors, Middle = one resistor and High = no resistor).

Thanks Duke.

Gary

[Duke W.]

Re: '63 Heater switch

I'm kind of stumbling around in the fog without a schematic of the switch or a switch to look at, but if the "high" position provides a direct path for system voltage to the motor, then it doesn't matter if system voltage is still connected to the motor via a parallel path through the resistors because this path is effectively shorted out.

Duke

[Gary Cederman]

Re: '63 Heater switch

Duke,

That's my whole point. I do have a schematic and that is what I see happening. I just wanted to make sure that it was the switch acting bad as oppose to me over looking something.

Thanks.