Chevy Trucks, Fan Motor Resistor

you could use a semiconducor speed control,

i will have look to see if i can find anything.

ps could you please supply the following

votage and wattage of motor.

thanks

If it were me i would go for these controllers 6-15 volts 3amp continuous 5 surge

http://www.maplin.co.uk/module.aspx?moduleno=9312 you would need one of these set to the desired speed for each of the settings

Various speed controllers

http://search.globalspec.com/ProductFinder/findproducts?query=12%20volt%20speed%20controller&se=ggka&setag=MOTN

I think you'll find the current at full speed to be around 30 amps.

My 2002 Chev truck had the resistor set up that you describe but the resistors themselves did not burn out. The thermal fuses in line them went open with the same effect as opening the resistor. I simply crimped a solid piece of wire in place of the fuse. I have no idea why they started use in a thermal fuse in that resistor setup as the older trucks did not have them. Perhaps for fire safety, I don't know but in two years I have not had any problem. There isn't anything in that duct to burn anyway. Check the fuses. If this is not the problem you have then I don't know why the actual resistors would burn out.

GA. Seek, and ye shall find.

To diagnose the problem,more information is required:What is the maximum current draw of the fan motor?Is the motor a series-field weakening speed control, or simply a voltage-drop control? Probably the latter, because they are the cheapest, but least efficient route.(How to tell which? if the resistance increases as the speed increases, it is series-field weakening)

1: If the wiring is melting, there are 2 reasons:

A: Is it melting along entire length or just at the terminal ends(does it have a bubbly appearance?)

1: Wire too small for load

B: Poor (loose,dirty,etc.) connections or underated connectors if melting only at the

connectors.

Solution for #1A:

Replace wiring with proper guage wire.30 amps will require #10AWG.If load amps is unknown,go with #10 AWG for safety margin.This is usually sufficient for most automotive purposes.

I recommend THHN, XHHW, or THWN-2 type insulation for the environment under the hood or dash.(90C rated insulation).

Solution to #1B:

Replace the socket/plug combination with a properly rated and properly installed connector.Emphasis on properly installed,ie; use a proper crimp tool for wiring, not pliers or channel locks.You need a displacement type crimp tool for proper connection and reliability.A loose connection can cause the connector plug or socket to melt, and via thermal conduction, other components may be affected, such as resistors, etc. Soldering is NOT a better connection than crimping if crimping is properly done.Solder tends to crystallise over long time periods and thermal cycling.When crimping connectors,be careful to fully crimp only the metal portion of the connector.The plastic beyond the metal is for strain relief and should be only very lightly crimped to the INSULATION.This prevents sharp bends at the crimp site and the resulting metal fatigue.

If resistor is the only component burning out, the problem is an under rated resistor(wattage too low).Replace with same value resistance,but higher wattage,or alternatively, use two resistors in parallel of double the original value(in Ohms).This will double the wattage, but resistance will be the same.To dissipate heat, mount resistors on firewall or aluminum heat sink.

Good luck.

Did you ever consider that the resistor might be going bcuz the motor is drawing a bit too much current ? And WHY is it drawing too much current ? Well, maybe the motor needs to be oiled....

I've seen this in the past so you might look into that

RoGrrr

Nissan Micras of the '90s had the same problems.

If you had an undamaged resistor and you measured its value, it could possibly be substituted by a higher wattage ceramic one.....(as someone has already mentioned in a similar way I believe....). We could help you.