Hot Heater Switch

Unknown

I have my new new wiring about 80% complete and I was checking some of my switches and systems today. I ended up tearing apart both the headlight and heater switch to clean corroded contacts.

The heater switch still does not seem to work correctly. The heater will work on the high speed function, but very poorly or not at all on the low speed setting. Also the switch seems to me to get excessly hot, I have a burn blister on one finger and a brand of coil marks on the other finger.

I am beginning to think the problem may be in the fan motor. Since the switch heats up I believe the current draw is too great, but I am not blowing fuses.

Any ideas of suggestions?

Thanks
Pat

Unknown

More than likely, the corroded contacts in the switch are creating too much resistance and, as such, are becoming hot. Try giving the switch contacts a shot of Cramolin/red oil while repeaptedly operating the switch. Good luck!

[Deleted User]

Remember the heater switch has a small coil spring that acts like a resister and it gets hot. Don't ever touch the back side. All heater switches work that way. If you have no low speed install a new motor. Walt.

Unknown

Dave53-7C wrote:

More than likely, the corroded contacts in the switch are creating too much resistance and, as such, are becoming hot. Try giving the switch contacts a shot of Cramolin/red oil while repeaptedly operating the switch. Good luck!

Dave:

I took the switch apart and cleaned the contacts with a wire brush on my dremel tool. This switch was not too bad with corrision, the headlight switch was another story, but it is now working fine after wire brushing the contacts on it.

Thanks for the suggestion. Whats Cramolin, similar to contact cleaner?

Pat

Unknown

walt's garage-53 wrote:

Remember the heater switch has a small coil spring that acts like a resister and it gets hot. Don't ever touch the back side. All heater switches work that way. If you have no low speed install a new motor. Walt.

Walt:

I was thinking on this problem last night and came to the conclusion that with the ceramic part and with an aluminum base the switch was made to handle heat in the coil spring and not pass it on to the knob.

I found an extra motor in my parts stash. I will temporary hook it up to test the switch.

Thanks

Pat

Unknown

SRCraftsman2 wrote:

Dave:



I took the switch apart and cleaned the contacts with a wire brush on my dremel tool. This switch was not too bad with corrision, the headlight switch was another story, but it is now working fine after wire brushing the contacts on it.



Thanks for the suggestion. Whats Cramolin, similar to contact cleaner?



Pat

Pat,



Think of your heater control as a rheostat, in essence, a variable resistor. If resistance to the flow of power through it exceeds design criterion, the switch will indeed get very hot. However, to suggest that it is normal for a switch to get so hot that it burns your fingers is obsurd. As originally intended on our cars, power flows through the heater and head light switches. On more modern cars, the same controls power relays which, in turn, switch power to the lights and heater. Years ago, some cars had a series of coils made from differing thicknesses of wire. In essence, resistors. The use of the heater dash control switched power at a relay which, in turn, directed power to the coil appropriate for the fan speed you selected. Check all of your connections as well as your fan motor. Also, make sure all related wiring is of the proper gauge. My car is 100% stock (ie; no headlight relays added) and the switches were're discussing don't get hot. The heater works perfectly and the headlights are bright.



Cramolin is a brand name for red oil. It was formulated for Bell labs to be used on telephone switching equipment. The beauty of this product is that if an electrical arc were to occur on contacts, the product recoats the area and provides ongoing protection. It is readily available at better electronic supply stores in a small red spray can.



I hope this info helps,



Dave