3 years ago I installed a ss dash in my 1970 El Camino, it was a used system I did everything I could think of to make all the connections correct, it has been working for three years but after about 6 months I had the high speed go out on the blower fan switch. Soon after I had the headlight switch burn up and I replaced them both. After I put the new switches in I was noticing a bakelite smell when the headlights were on. I pulled it apart and pulled each wire on the light switch plug and tightened the terminals, it did not help, You can feel the heat in the switch by toughing the steel stem of the knob. It seams to cool down if I dim the interior lights, Now my Blower switch has burned up again. I don’t think Im getting bad parts . Any thoughts?

Any thoughts?

Heat is generated by poor connections.
Sounds like you got a bad light switch that doesn't make good connections internally to me.

I would check all of the grounds. Not sure about a 70, but on my 66 the dash is steel, and things like the wiper switch ground through the dash. IIRC, the headlight switch switches power for the head lights, which ground separately at each light, but dash lights probably ground through the panel.

Heat is generated by poor connections.
Sounds like you got a bad light switch that doesn't make good connections internally to me.

I agree with Dean. The switches have become too resistive. If you turn the switch to the on position (so that the lights are turned on) and measure the voltage, with a digital voltmeter, between the two terminals of the switch you should see a voltage of less then 0.100 volts, that is one tenth of a volt. If you see more than that the switch is considered to be loosing too much power and has "failed" in the technical sense.

If the switch is new and you get a reading greater than 0.100 volts then the switch is not manufactured very well.

A little more technical view:
Watts lost is volts between the switch terminals (measured at the bass terminals coming out of the switch, not at the connectors that are attached to the brass terminals) multiplied by the current through the switch.

Example: A set of headlamps are drawing 14 amperes of current. The voltage across the switch is 0.20V. 14 x 0.20 = 2.80 watts (that's a lot) and the resistance of the switch is 0.20/14 = 0.014 ohms. With this much power loss the spot weld bonds to the contacts (or in cheap switches the bonding rivets) are considered to have failed.

A good switch that is rated for 20 to 30A is around 2 milliohms (0.002 ohms); that is 0.040 volts to 0.060 volts depending on the current through the switch or 0.060 volts x 30 amperes = 1.8 watts.

You can check most switches this way. The amount of heat you feel from the switch is proportional to the power loss (watts) lost across the switch.

Ron

The heater blower switch in my car is burnt up too. So bad the connector melted, Been like this even before I got it. The only thing I can imagine is a faulty blower motor drawing to much amperage. AS far as the headlight light its is the main resistor for all the lights inside,. I would likely just change it

A faulty blower motor drawing to much amperage should blow the fuse.
Like I said heat is generated by a bad connection.

Sounds like I need to buy a couple more switches, I put the headlights on relays, to lower the amps going through the switch, but it still gets hot when the dash lights are on. Maybee I should change all the bulbs in the dash, There are alot more bulbs in a SS dash than a sweep dash and I also have a console.

Sounds like I need to buy a couple more switches, I put the headlights on relays, to lower the amps going through the switch, but it still gets hot when the dash lights are on. Maybee I should change all the bulbs in the dash, There are alot more bulbs in a SS dash than a sweep dash and I also have a console.

Ah, then it's the variable resistor (rheostat) that is getting too hot. You might try taking a few bulbs out of the console and dash or changing the type of bulb to ones that use less power (lower watts).

Ron

Since it is a used harness I would remove all of the terminals in the connections that are getting hot and clean them with a wire brush.

An update to my original problem...After putting the headlight on relays I have not had any more problems with the Headlight switch. My A/C fan switch went out again, The last time I replaced the the switch the terminal plug was melted and the terminals were overheated. I discarded the plug and replaced the terminal ends with individual wire ends but here I am 16 months later replacing the switch again. THEORY; could an alternator that can not keep up with amperage that is being drawn by the system be causing this? My headlights dim at Idle and my fan also slows down. could upgrading the alternator help? Or will this just increase the amperage to help burn up the switches.

I would check all the grounds like rkd said and maybe test the blower motor off the car and see if the wires get hot because its drawing too maney amps like dean said.The blower motor may not be grounded to the body properly.You shouldnt have to alter the way the harness is designed because it doesnt fix the problem and you take the chance of burning your car down.Also check the blower resister for any problems.Could also posably be a short to ground someplace or two wires shorting together.Ill remove my entire harness and inspect every wire if I have to even if it means removing all the protective tape and retaping the entire thing.

My A/C fan switch went out again, The last time I replaced the the switch the terminal plug was melted and the terminals were overheated. I discarded the plug and replaced the terminal ends with individual wire ends but here I am 16 months later replacing the switch again. Since many thing might have been changed....... The dash has a A/C fan switch, what was the car originally, a A/C or non A/C car? What blower are you using? What color wires were melted?

Original A/C cars had a relay for the high speed blower, do you have one?

THEORY; could an alternator that can not keep up with amperage that is being drawn by the system be causing this? My headlights dim at Idle and my fan also slows down. could upgrading the alternator help? Or will this just increase the amperage to help burn up the switches.

Short answer, no

Ill post my findings in a few days. Need to pull it all apart AGAIN!!!

Hummm What is your system voltage? (measure the voltage at the fuse box)

Ron

This is an original A/C car. When I checked the voltage at the fuse box it was 12.06v when I pulled out the switch I could tell that the switch had been hot but all the wire connectors were tight and looked good. With the new switch in place there is 5 positions on the switch: off, very low, low, medium and high. Very low is almost not moving air at all and you cannot hear the fan turning. When I replaced the fan motor 5 years ago I do not remember if there is a ground to that fan motor. I have a ground strap from the engine to the same point on the firewall as the a/c wire harness ground.
Question: does the ground wire in the a/c harness go to the fan motor or does it ground by being fastened? I may have to Pull the inner fender out to find out!