| [GMCnet] Max/hi speed A/C help [message #299200] |
Sun, 17 April 2016 19:29  |
larry erd
Messages: 132
Registered: August 2010
Karma: 0
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Senior Member |
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My A/C will not work on MAX/HI any more, I know this has come up on
this Forum before but I need a refresher. I believe the Hi speed fan
bypasses
the rectifier and is a direct connection to the ALT.. When I put the A/C
on Max
it shuts the A/C off. Direction please.
Thanks for your help
Larry Erd
77 ex kingsley
Lake Wales Fl.
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| Re: [GMCnet] Max/hi speed A/C help [message #299202 is a reply to message #299200] |
Sun, 17 April 2016 19:43  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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larry erd wrote on Sun, 17 April 2016 19:29My A/C will not work on MAX/HI any more, I know this has come up on this Forum before but I need a refresher. I believe the Hi speed fan bypasses the rectifier and is a direct connection to the ALT.. When I put the A/C on Max it shuts the A/C off. Direction please.
Thanks for your help
Larry Erd
77 ex kingsley
Lake Wales Fl. I think the current flow for the high speed is the same on all models. Here is a picture of the flow from a 73/74. The 77 is only different for lo or med/lo. Yours has a tan wire for one speed that is not shown on this, but it is irrelevant to the high speed. Get your continuity checker or multi-meter and find the loose or corroded connection, blown fuse, broken wire, whatever.
[Updated on: Sun, 17 April 2016 20:09] Report message to a moderator |
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| Re: [GMCnet] Max/hi speed A/C help [message #299205 is a reply to message #299200] |
Sun, 17 April 2016 20:18 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Most likely is a melted loom connection at the Hi blower relay. This happens on GM when that connection gets oxidized. May need a new relay due to heat from the meltdown. Less likely is your alternator is not actually working and you haven't yet noticed.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Max/hi speed A/C help [message #299220 is a reply to message #299200] |
Mon, 18 April 2016 07:23 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I noticed you are a 77. There is a Hi delay relay that can also fail. You can simply repatch the connectors at the Hi blower relay to circumvent the delay relay. No wires cut cut. Just take the delay out of the loop.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Max/hi speed A/C help [message #299255 is a reply to message #299220] |
Mon, 18 April 2016 14:00 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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JohnL455 wrote on Mon, 18 April 2016 07:23I noticed you are a 77. There is a Hi delay relay that can also fail. You can simply repatch the connectors at the Hi blower relay to circumvent the delay relay. No wires cut cut. Just take the delay out of the loop. You are right. I should probably take the fan speed/blower control circuit diagram from 1978 and generalize it for all years (annotate the differences between year models on the diagram).
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