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Old 01-17-2013, 06:36 PM
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Blower Motor blows fuses on high

My grandson has a 75 Trans Am that blows fuses all the time when switched to the max position. It's OK on low and medium but craps out on high.
Where do I start to trouble shoot. Apparently it's shorting to ground somewhere.

Switch, relay ??

How to trouble shoot or hot wire to be on high all the time during the cold weather were having?

Need some assistance ASAP

Thanks

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Old 01-17-2013, 08:57 PM
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blowing fuses

have you checked your blower motor resistor?
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walt03 (01-20-2013)
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Old 01-18-2013, 08:26 AM
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I checked the fan resistor all OK

There are many wires that are behind the distributor that if they were hot could melt the insulation on the wires.
Thats this weekend work

Beside this the cigarette lighter and glove box light are also blowing fuses.

Its tough to teach your grandson the way to fix things when your grappling for answers yourself.. You know what I mean?
Thanks and keep the possible fixes coming
Walt
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Old 01-18-2013, 08:57 AM
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Just a thought. Disconnect the connector that goes to the blower. Turn the switch on high. If it blows you'll know its not the blower,but something in the harness or dash. If it dosen't blow, install a fuse with say a 1 amp rating and see if it blowes with the blower still disconnected. If it does there probably a short or at least a resitive contact(oil or water) being made somewhere in the harness.
If it doesn't blow with either fuse with the blower disconnected,and the switch on high you'll know its something past the connector that isn't right. I don't know if the blower has a resistor like someone mentioned that is in the circuit when the switch is on high or not. I'm just guessing that the resistor is in the circuit to lower current to the moter when the switch is on a lower setting.
Is there any chance that something is physically keeping the fan from spinning freely(bad bearings, or trash near blades)?
FWIW
ssmonty
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walt03 (01-20-2013)
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Old 01-18-2013, 10:11 PM
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I'll agree with SSMonty that the motor could be dragging and make the suggestion that you drill a 1/8 hole in the end of the motor cover, give it a shot of air to blow out the 35 + year old grease and squirt some TriFlow (teflon oil) in the hole to give it some good lubrication. Don't use WD40, just makes it sticky.
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Old 01-19-2013, 12:03 PM
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You have a switch connector or relay connector that is badly corroded causing excessive resistance and consequently high amperage draw.

Vince
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Old 01-19-2013, 01:48 PM
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When the fuse panel fuse blows, taking out the low and medium speeds, could the relay be grounding out and not taking out the in line fuse between the relay and motor??
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Old 01-20-2013, 03:02 PM
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I just had a nearly identical problem with mine. The bearings were shot and the brushes were worn out.
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Old 01-20-2013, 06:51 PM
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I got it fixed.

It turned out to be a bad fitting line fuse holder that once changed by a previous owner, An after market lock end pigtail was used with the original GM fuse holder.

Looking closely you could see the nylon fuse holder had burn discoloration and only after getting it to work and blow more fuses I decided to replace it with a completely new fuse holder and crimp it into the old line.

It worked

Thank you to all people giving me tips on how to trouble shoot this.
Each one helped.

The blown fuse on the cigarette lighter and glove box was the result of some black tape falling off a female aftermarket connector in the heat of the summer and shorting out against the radio case.

You guys are great and I really appreciate you coming to my rescue,

My son-in-law and grandson learned a lot too.
Walt
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Old 01-21-2013, 10:21 AM
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About the only things that occur regularly on this subject is the blower motor pulling to much amps due to bad bearings or something restricting it, and burnt connections causing excessive amperage draw. Glad you found the problem but it sounds as if you need to do a complete electrical system check.

Vince
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Old 01-21-2013, 07:40 PM
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I agree Vince.
Thanks for your comments.
Walt
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Old 01-22-2013, 06:53 PM
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Quote:
Originally Posted by walt03 View Post
I agree Vince.
Thanks for your comments.
Walt


Your quite welcome Walt.

Vince
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