Heater switch melted… Why?

[2INSANE]

For about a year, my heater switch kept cutting in and out. A good tap on the dash usually got it working again. But now it is totally shot. I pulled out the switch and wiring and found the positive terminal connections were toasted and the wire was hot to the touch. Looking at the wiring diagram, I see only 1 ground. Any ideas why the positive terminals be getting hot?

 

[Squibbly]

It got too hot.

What color are the wires going into that connector?

 

[antennaclimber]

Poor connections, a little bit of corrosion and a moderate current draw will cause failures like that. Resistance in a poor electrical connection will cause things to heat up.

Like all electrical connections, they need to be clean and free of any contaminates that cause a poor connection. In higher current demand applications, it becomes even more critical to have good connection. A heater fan will draw a fair amount of current. The pictures of the dull and dirty brass tabs on the connector and switch are indicative of a much needed cleaning.

The blower motor only needs one ground wire, the switch simply connects the 12 volt positive to the blower motor resistors on the fire wall. The Low position has more resistance, the Medium position has a little less resistance and on High it is directly feeding the blower motor from the 12 volt system.

 

[antennaclimber]

What color are the wires going into that connector?


Brown is the 12 volt feed from the fuse box.

Yellow is the Low fan speed.

Light Blue is the Medium fan speed.

Orange is the High fan speed.

 

[Squibbly]

What color are the wires going into that connector?


Brown is the 12 volt feed from the fuse box.

Yellow is the Low fan speed.

Light Blue is the Medium fan speed.

Orange is the High fan speed.

I assume it is the brown wire that is cooked?
Agreed, bad contact somewhere.

Same reason your battery cables will smoke when you try to start your truck if your grounds are dirty or your connections to the clamps have corrosion.
Resistance.

Banging on the dash was probably about as good for the electrical system as this throwback.

A little atomized spit should do it.

 

[2INSANE]

The toasted terminal is the brown wire. Looks good but the terminal is not. Following the brown wire, it is connected to a single terminal which looks good.

I think over the years of using the heater all the time, dust, corrosion, moisture in the air etc prob caused a poor connection which over worked the supply.

I’ll put a thicker ground wire on the motor, clean and replace the switch, terminal…

Anyone got a good used climate control switch panel and heater switch wiring they could sell me? Like ASAP?

 

[Squibbly]

The toasted terminal is the brown wire. Looks good but the terminal is not. Following the brown wire, it is connected to a single terminal which looks good.

I think over the years of using the heater all the time, dust, corrosion, moisture in the air etc prob caused a poor connection which over worked the supply.

I’ll put a thicker ground wire on the motor, clean and replace the switch, terminal…

Anyone got a good used climate control switch panel and heater switch wiring they could sell me? Like ASAP?

Make sure the fuse is the correct one as well. People have been known to just use a jumper wire in place of a fuse on occasion

 

[nyoffroad]

That switch is available at many auto parts store, the plug is a bit harder to find new.

 

[MarcusOReallyus]

I’ll put a thicker ground wire on the motor, clean and replace the switch, terminal…

You don't need a thicker ground wire, you need clean connections.


(Not that a thicker ground wire will hurt anything, but don't think it's going to do anything about this problem.)