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| Heater blower problems [message #221564] |
Sat, 07 September 2013 21:27  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Senior Member |
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OK, trying to figure out what is going wrong with a 77 kingsley A/C blower fan.
this was just picked up by a fellow GMCer, and getting ready to make a road trek west.
the PO had just installed a new fan motor. but,
some wires had been fried...
we fired it up, and the lead to the motor melted, and some other wires fried. and when I took out the fan motor to bench test, it too was fried... up in smoke.
so installed a new fan motor, re-did the ground connection.
there is a heavy gauge red wire, that had a fusable link on it, that was burnt off. so I replaced that with a 16ga fusable link.
I removed the Noise supression capacity/coil thing from the equation, because the wires were fried now... could not find any replacement, and i thought maybe that caused some issue.
then there is a relay of sorts up high, and that was disconnected, and bypassed.
I looked at my 75 palm beach, and I connected up the wires to match, with the exception of that relay, witch really is just not at all on my 75.
now it runs good. however the heavy red wire, and the fusable link are getting hot. but not as quickly or instantly as it did just before with the burnt up new fan.
tomorrow, I am going to replace the connector off that heavy red wire, because I think it is a poor connector. and I am wondering if I should repace the fusable link with a bigger one, or a actual fuse? (my 75 has a fuse instead of a fusable link).
thoughts?
here are some pictures on my blog.
http://lqqkatjon.blogspot.com/
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Heater blower problems [message #221568 is a reply to message #221564] |
Sat, 07 September 2013 21:51  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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| lqqkatjon wrote on Sat, 07 September 2013 21:27 |
OK, trying to figure out what is going wrong with a 77 kingsley A/C blower fan.
this was just picked up by a fellow GMCer, and getting ready to make a road trek west.
the PO had just installed a new fan motor. but,
some wires had been fried...
we fired it up, and the lead to the motor melted, and some other wires fried. and when I took out the fan motor to bench test, it too was fried... up in smoke.
so installed a new fan motor, re-did the ground connection.
there is a heavy gauge red wire, that had a fusable link on it, that was burnt off. so I replaced that with a 16ga fusable link.
I removed the Noise supression capacity/coil thing from the equation, because the wires were fried now... could not find any replacement, and i thought maybe that caused some issue.
then there is a relay of sorts up high, and that was disconnected, and bypassed.
I looked at my 75 palm beach, and I connected up the wires to match, with the exception of that relay, witch really is just not at all on my 75.
now it runs good. however the heavy red wire, and the fusable link are getting hot. but not as quickly or instantly as it did just before with the burnt up new fan.
tomorrow, I am going to replace the connector off that heavy red wire, because I think it is a poor connector. and I am wondering if I should repace the fusable link with a bigger one, or a actual fuse? (my 75 has a fuse instead of a fusable link).
thoughts?
here are some pictures on my blog.
http://lqqkatjon.blogspot.com/
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Everything you need is in the post here
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=220229&rid=2083&srch=fan+blower#msg_220229
and the four photos and captions starting here:
http://www.gmcmhphotos.com/photos/electrical/p50598-heater-and-dash-air-conditioner-wiring.html
The first picture is the blower motor and dash A/C power schematic.
The next three pictures and captions show the current flow for each fan speed, and the colors of the wires for a '73. I don't know if the colors of the wires are the same for all years.
FYI, you can see from the diagram that the fuse for the big red wire was originally 30A, and that is for the high speed setting, in which the blower relay connects the blower directly to the alternator, boosting the voltage by 0.7V higher than the battery. There should be NO CURRENT ON THAT WIRE WHEN THE FAN IS IN LO OR MED SPEED, ONLY HI. If it is getting hot when LO or MED speed is selected, something is miswired, and that could easily fry the blower motor.
Check out the post and pictures and captions.
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| Re: Heater blower problems [message #221571 is a reply to message #221568] |
Sat, 07 September 2013 22:05 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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Forgot to mention, CHECK THE ALTERNATOR VOLTAGE AT THE CENTER POST OF THE ISOLATOR. It should not be much over 14 volts. If it is way high, you need to fix that before it fries other stuff besides just the blower motor.
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