Heater fan switch

[Jeff Balazs]

In view of recent events at Paul's house I think it wise to mention something I had occur recently.

 

I had installed a new twist knob rheostat type switch to control the fan for my heater. It never really worked smoothly and had continuity dead spots in it's movement. The other day I decided to investigate. This was the second such new unit I had purchased and both had similar quality issues. It is the most common one you see on ebay with the light up knob. I also had an old unit that I had gotten from a member here and had cleaned up but never used. It is a 3 position switch.

 

I decided to try the old switch and it worked but got very hot in short order. When I say hot I am talking to hot to hold onto. And this was a couple of minutes after I had shut it off. The others were just warm by comparison. So out it came. I know electrical item's like this can and do produce some heat but this was more than a bit scary. The quality of the reproduction stuff that is available is also very questionable. These sorts of items are something that we should be able to trust. They should work smoothly and operate consistently.

 

I went ahead and sourced an NOS Borg Warner 3 position pull type HD switch that looks to be of excellent quality as a replacement.It is of an entirely different type of construction and looks very substantial. Hopefully it will give good service and operate properly.....and without a lot of heat. I will report back for those which may be interested. The vendor has more of these.

 

I brought this up to make all aware that there are potential fire starters in our old vehicles ........ little things like this switch...... which could result in something horrific. We all need to be very careful when it comes to things like this. Frequent checks into these things is a good idea. The whole experience made me feel very good about the master battery switch I have installed and use religiously.

 

Jeff

[1952B3b23]

Good call on bring that up Jeff. Another thing to watch out for is wire gauge size used in the truck. Especially 6 volt systems will draw more current than a 12 volt for a given set of conditions. The amount of heat generated by faulty/ undersized electrical components can be really surprising and easily cause a fire.

-Chris

[John-T-53]

Yes, it's a good idea to check all switches to make sure they're working correctly. Rheostat switches like the heater switch do produce heat - in these cases it's important they are built correctly and anything combustible is not near or touching the switch.

I had a smoking ignition switch in my Chevy last year - due to a loose connection in one of the contacts. If any of the contacts on the back of a switch are loose (mainly from a rivet coming loose or insulation breaking down), replace it! This causes the current path to get smaller creating heat. 

 

Light switches also can produce heat. Also - Ignition voltage resistors too (if so equipped).

[MBF]

Any resister with a load on it is going to get hot.  The rheostat switches of the older design/construction were built to create and stand heat since their job is to burn off current in order to slow the blower motor.  If the body of the switch around the rheostat is ceramic you're probably ok with it.  Make sure that nothing comes into contact with it as the coil may get hot enough to glow-especially if there is an issue with the blower motor or its ground.  In newer vehicles these resistors were put in the heat ducting to allow them to get rid of the excess heat more safely.

[Jeff Balazs]

The quality of a lot of electrical components is definitely not what it used to be.

A couple of the faulty components I ran into when putting my truck together were made in Mexico. And I have already replace a couple of bulbs.......one chinese Wagner......and the other the manufacturer was so proud of it had no name or point of origin?

Where ever possible I have bought American.........but it is getting harder and harder to source.

 

I really brought this up to remind people that it is not a bad idea to check electrical components from time to time. I guess what I am trying to say is just because something operates doesn't mean it problem free. The amount of heat I felt at the terminal of the one old switch I tested was way too much to be safe. I am glad I burnt my finger and not something else.

 

Jeff

[Desotodav]

You raise a good point Jeff. I am fortunate to have a friend who works in the electrical components field, so I had him service all of my old switches etc before they went back into the 52 truck. I have wondered recently whether I should install a cut-off switch on my battery cable just in case a power issue might develop whilst my truck is parked safely in my garage (as Paul's was). I suppose that would offer some peace of mind. I too have burnt my finger when I shorted my battery out on the metal hold down frame and almost set fire to my truck and garage a while back!

[MBF]

I know that there are some here that think a cutoff switch isn't necessary.  I rewired my truck several years ago and have not had even a single fuse blow since then. I will tell you having been to many structure fires as a volunteer firefighter, that some of these were caused by an almost new vehicle in the garage.    I've also seen what mice can do to a wiring harness first hand, and I'm not giving the little buggers another chance to ruin my toys.   I had a real nice MACK cabover parked right alongside of my garage.  I was at a structure fire during a very severe thunderstorm with my FD.  My daughter called me to tell me there was smoke coming out of the grill of the MACK. I hurried home to investigate.  It turns out that Mice had chewed the insulation off an area of the pos batt cable, and the rain and wind from the storm caused it to short out against an uninsulated braided power steering hose.  The short had burned through the braiding, and the oil was now dripping on the hot shorted cable.  The smoke was the oil just starting to burn.  There was almost a gallon of power steering fluid in the reservoir that would have gravity feed the leak in the hose.  Had that happened I would have lost the MACK, and most likely my garage and everything in it because my FD had all equipment committed at the structure fire on the other end of town.  Yup-call me what you want, but I'm one of those guys that never leaves battery connected on old vehicles while they're unattended for more than a little while.

Edited February 13, 2014 by MBFowler

[Scruffy49]

Pulled the battery out of my 69 D100 a year ago when the mice started eating the wiring harness. The 49 battery is not only disconnected, it is 20 years old and probably so far beyond flat lined that it is irrelevant. I'm just too lazy to pull it until I absolutely have to...

[Jeff Balazs]

I got the new Borg Warner switch swapped in. All is good and it does not seem to even get warm in use. I will keep an eye on it but I feel much better about the quality of this component. NOS...... Made in the USA .....when that meant something. I would urge all reading this to check the condition of the components like this in their trucks and cars. You may be surprised at what you find......it may work......but put your hands on it while it is and see how warm it gets. If it get's too hot to touch chances are there is a problem that needs attention.

 

Mike I am of the same opinion as you regarding this. I don't really care if people think I am being overly cautious. Rather be safe than sorry. When the battery is disconnected less stuff can go wrong. I installed a HD keyed battery switch in the truck and I will use it religiously.

 

Jeff

[gramps1951]

if this new switch works out well for you could you post the part number of it for us thanks.  neil