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#1
10-15-2020, 04:45 PM
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Loss of high setting on blower motor
Hello all, my 78 T/A recently lost its high speed...I have a vague memory of this happening about 20 years ago, but I can't remember what the problem was; I don't think it was the relay or resistor, but just can't say for sure - anyone else know what the problem is?
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78 White T/A, Carmine interior, Fisher T-tops, WS-6 package, 3.08 gears, a/c, rear discs. Original 403 with 300,000 miles replaced by new Pontiac 455 (roller everything, 6x-4 heads, Performer manifold, Hooker Headers, Hughes converter, Cliff's Q-jet) - I only get 12 mpg! |
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#2
10-15-2020, 06:01 PM
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What I've seen the most of, is a melted connector, in the hot wire, between the high speed relay and alternator.
Clay |
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#3
10-15-2020, 07:39 PM
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I don't have a 78 TA wiring diagram to look at, but GM cars of this vintage had an in-line fuse that was for high speed only, along with the relay that Clay refers to.
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My Pontiac is a '57 GMC with its original 347" Pontiac V8 and dual-range Hydra-Matic. |
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#4
10-15-2020, 08:27 PM
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I have heard about a fusible link between the alternator and blower motor, but I just have never seen it on my car...
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78 White T/A, Carmine interior, Fisher T-tops, WS-6 package, 3.08 gears, a/c, rear discs. Original 403 with 300,000 miles replaced by new Pontiac 455 (roller everything, 6x-4 heads, Performer manifold, Hooker Headers, Hughes converter, Cliff's Q-jet) - I only get 12 mpg! |
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#5
10-15-2020, 08:47 PM
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It’s the thick red wire.
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#6
10-15-2020, 10:35 PM
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Most of the Pontiacs of that vintage had a 30 amp fuse at the output stud on the alternator. It would over heat and melt the fuse holder and blow the fuse . The factory fix was to cut out the single 30 amp fuse and replace it with two 20 amp fuses installed in parallel. If you don't have the fuse check for battery voltage at the high blower relay located at the AC case near the blower motor. If no voltage trace the wire back to the alternator.
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