Electrical question for ya'll.
 

My blower motor has been blowing 30a fuses off and on. The motor will run for a while then the fuse will blow. With the ignition off I disconnected the purple wire from my a/c blower motor. I tested for ground on the spade on the motor and got a reading of .5ohms, the same reading I got when touching the probes together. I tested back through the switch (in HI position) and got a reading of 12.5ohms. What would be normal readings? Is the switch or blower or both bad?

I just checked a couple of blower motors and got .6 and .7 ohms which is very close to your reading on your motor. It sounds like you are loosing contact slightly in your switch but that would not cause blowing of the fuses.

I suspect that you have a blower motor problem and you should be able to check the draw when it is running if you have the right ammeter setup. ( I use an ammeter that read by placing it over the wire).

Jim

put a 35 in and call it good :D

Yes, it sounds like your blower motor is tired and pulling too much amperage blowing the fuse. Usually, not always, but usually, a short to ground will blow the fuse instantaneously.

There is a ? rheostat ? Up under the heater box. Mine was doing the same thing. I found the ? rheostat? thing and replaced it. Heater works like a charm.

Sorry I don’t know exactly what you call it. Its hidden up on the heater box though, just follow the wires you'll find it

That is a resistor in the heater box...normally they either work, or don't work. (Although, there is the chance that it is at fault)
IMO, I think the motor is getting old and tired. Does it make any squeeling or rumbling noises? Drill a real small hole dead center on the sheet metal of the blower motor. You don't even need to remove it from the truck. There is a raised nipple, drill it in the center, and then put some graphite powder...or spray in the hole. Use a small dab of silicone to re-seal the hole. Do not operate untill sillicone is dry.
If this solves the problem, then your motor is on borrowed time. however, i have seen blower motors fo 5 more years after doing this. Personally, mine is about to hit 4 years on this repair...and still blowing hard too.

$13 dollars at O'reilly's for a new blower motor, now I just gotta find the time to install it. Thanks for the help guys!

mannn, last time i checked into a new blower, I was quoted 45 bucks....which is why mine has silicone on the end of it.
Still, it is a quickie that does work.

you like those quickies..................................fixes that is

I like them quick AND cheap. ;)

but do you like them clean or greasy & bloody? repairs that is.

lol