Defrost fan rehab and rebuild thread (fresh air fan), or How the heck do if fix this thing? |
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Defrost fan rehab and rebuild thread (fresh air fan), or How the heck do if fix this thing? |
DRPHIL914 |
Jan 21 2021, 08:55 AM
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#54
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Dr. Phil Group: Members Posts: 5,808 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States |
I have been dealing with this for 12 years, a non-running defrost fan. i even pulled this out 2 years ago and rebuilt it with new flapper seals and main body seal then made sure fan turned but didnt bench test the motor or resisitors, so as a result it still does not work properly. i will be documenting this because 914rubber and Mark will soon be putting together a kit for this that includes all the hardware seals and even a motor i believe, BUT i still have problems and questions!!! so i am starting this thread to get information on diagnosing the common causes of it not working and how to fix it, and then document the rebuild and replacement of the motor, fan, resistor and maybe the control unit in dash. Others have documented the reinstallation of the fan and the cables so i will not duplicate that. and we may want to link other threads hear that have done that as well.
Mark is sending me a kit soon, so while i wait for it, i will have to get some more information about the wiring and resistors function and how to test them . I had this out last week and tested 3 different control units due to thinking that my issue was a control issue, because it runs on one speed, #2, and anything else does not work and it will then throw the fuse. most assume this would be caused by bad slider unit but i tested 3 of them and 2 are like new with no wear on the sliders , still same result. so i am suspecting the resistors /plug aparatus . If anyone has done this and cares to share how to examine and test that for proper function, lets start there. Resistor function, which lead is which and examination of the control units I will take pictures of mine tonight and post those soon. once this figured out and fixed i will do a full step bystep on reassembly too. Looking for lots of help and input on this, thanks!!! Dr. Phil |
framos914 |
Jan 21 2021, 12:18 PM
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#55
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Member Group: Members Posts: 125 Joined: 15-May 14 From: Corona California Member No.: 17,353 Region Association: Southern California |
I went through this a few months ago. Since I had the gas tank out, I thought I would tackle the non working defrost fan. I removed the fan for bench testing.
I checked resistance between the hot pin on the unit and each of the other 3 pins. I did get 3 different resistance values (should have noted the resistance values). Next I connected 12 volts to the unit and applied ground to each of the other 3 pins. I got the 3 different speeds. I turned my attention to the control lever. Since none of the 3 speeds worked I concentrated on the part of the slider contacts that was common to all 3 wires. Must have just been corroded because after a good cleaning of all contact surfaces the fan worked normal. I removed, cleaned and lubed the windshield wiper assembly while I was in there. Of course it was a PITA reinstalling the fan. Ian has a good video on how to install fan. |
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