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1986 Cadillac Fleetwood Brougham
06-25-2017, 01:41 PM
Post: #1
1986 Cadillac Fleetwood Brougham
Good Morning,
Hopefully someone out there can help me. It started when the blower would come on most of the time. It would have days where it would not come on at all.
It started becoming more frequent. The summer, here in the Northeast has been brutal so far. No A/C makes me a miserable person.
Anyway, I tested the voltage going to the motor. The voltage was about 13 as it should be. So, it thought the windings in the motor were going and causing this.. It is getting power, however it is not turning on.
The new motor did the same thing. I returned the motor and put the old one back in.
I figured i would test the ground next. I got a piece of an electrical cord, from a lamp, put it on the ground screw next to the blower motor and put the other end on the alternator bracket. The blower kicked on.
However, the lamp cord got really hot on the blower motor end, It also did not shut off when i turned off the A/C and even after i shut off the car.
So, i realize now i have a ground problem. But, why is my bypass line getting so hot? And why won't the blower shut off even after i turn the car off?
I forgot to mention that before i grounded the lamp cord to the blower motor, i did disconnect the ground from the car. I also checked the continuity between the end of the ground wire at the blower motor and the other end of the wire at the junction box. There was continuity.
Please help if you can. Thank you for any advise anyone can give.
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06-26-2017, 12:07 AM
Post: #2
RE: 1986 Cadillac Fleetwood Brougham
Don't have a diagram handy for that vintage Cady but I can tell you that a piece of lamp cord is likely #16 or #18 gauge and is NOT heavy enough to run a blower motor that typically needs near 20 amps on high speed. That's why the wire gets hot.

What I can tell you about that car is there's several relays and some modules that control fan speed, especially if it's got climate control which sorts out the fan speed via ambient temp and your desired settings of cabin temp. After that it gets fuzzy in my mind, but the basics are the control module sets the fan speed through a relay and a resistor (just like most) and also the high-blow relay. (just like most) Perhaps a gander at some parts pages (Rock Auto?) will give you an idea of what the part looks like (so you can find them) and you can do some testing once you figure out where those parts are located.
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06-26-2017, 05:47 AM
Post: #3
RE: 1986 Cadillac Fleetwood Brougham
Just to add a bit of info... The motor probably has power all of the time directly from the battery. The controls that Rupe is speaking of controls how and when the "ground" is supplied. When you supplied a constant ground to the motor it can't shut off. You bypassed the control mechanism.

Please let us know how you make out with this problem.

Thanks for using the forum,

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