 Fresh air fan problem |
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| bdstone914 |
 Aug 28 2023, 08:25 AM
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#1
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bdstone914  Group: Members Posts: 4,521 Joined: 8-November 03 From: Riverside CA Member No.: 1,319  |
Only have the middle speed on the fan. Tested to motor and it runs full speed when powered directly at the motor. Pulled the control and cleaned the contacts.
I am wondering if the problem is in the terminal block at the fan. I am thinking there was a resistor in there. Any ideas? |
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| 930cabman |
Aug 28 2023, 08:41 AM
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#2
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Advanced Member Group: Members Posts: 3,061 Joined: 12-November 20 From: Buffalo Member No.: 24,877 Region Association: North East States 
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I have never had one apart, but I'll bet the technology is near ancient. Trying to recall a similar issue with only one speed working on an old Dodge and a failed resistor just might have been the cause. Probably 40 or 50 years ago
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| BeatNavy |
Aug 28 2023, 10:55 AM
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#3
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region
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There are a pair of resistors in the housing of the fan. IIRC, high speed grounds by bypassing both resistors, mid speed grounds through one, and low through both. Not 100% sure that's how it works, but something like that.
My low speed resistor burned up at one point from too much resistance so I only have medium and high as well. I remember seeing the little puff of smoke come up through the vent... |
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| jim_hoyland |
Aug 28 2023, 11:09 AM
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#4
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Get that VIN ? Group: Members Posts: 9,292 Joined: 1-May 03 From: Sunset Beach, CA Member No.: 643 Region Association: Southern California
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I've wondered whether a more efficient blower could replace the original. The fresh airfaninmy '91 Volvo really puts out ?
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| DRPHIL914 |
Aug 28 2023, 11:32 AM
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#5
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Dr. Phil Group: Members Posts: 5,766 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States
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QUOTE(bdstone914 @ Aug 28 2023, 10:25 AM)  Only have the middle speed on the fan. Tested to motor and it runs full speed when powered directly at the motor. Pulled the control and cleaned the contacts. I am wondering if the problem is in the terminal block at the fan. I am thinking there was a resistor in there. Any ideas? QUOTE(jim_hoyland @ Aug 28 2023, 01:09 PM) I've wondered whether a more efficient blower could replace the original. The fresh airfaninmy '91 Volvo really puts out ? does it blow a fuse if you leave it on low or high? mine did this and it turned out the previous owner had but the fuse block back in but crossed the wires so medium worked but high and low blew the fuse because it was shorting out. regarding the resistor thats possible the resistor is gone or its just that the controller has warped and its not touching on low . to test this you can pull the wires and connect a different controller to see if thats the issue. @jim_hoyland Jim, new fans with new motors are available and they really crank on high. the old fan bearings could be the issue and not letting it spin freely. @bdstone914 If the resisitors are bad( you can test them) i think i have a second set of good ones in my box, let me know. Phil |
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| DRPHIL914 |
Aug 28 2023, 11:38 AM
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#6
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Dr. Phil Group: Members Posts: 5,766 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States
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this might help- some info about the resistors etc in this tread
http://www.914world.com/bbs2/index.php?sho...=351152&hl= |
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| TonyA |
Aug 28 2023, 06:37 PM
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#7
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Nachmal Group: Members Posts: 468 Joined: 17-November 16 From: Hilltown PA Member No.: 20,596 Region Association: North East States
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QUOTE(BeatNavy @ Aug 28 2023, 12:55 PM) There are a pair of resistors in the housing of the fan. IIRC, high speed grounds by bypassing both resistors, mid speed grounds through one, and low through both. Not 100% sure that's how it works, but something like that. My low speed resistor burned up at one point from too much resistance so I only have medium and high as well. I remember seeing the little puff of smoke come up through the vent... Did you snort that puff of smoke (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/lol-2.gif) |
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