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 |
DRPHIL914 |
Jan 25 2021, 06:14 PM
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#55
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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 |
took the sucker apart and retested the resistor pack without being hooked up to motor,
values are: Low- 1.5 Medium- 3.4 high- 1-1.5 @Superhawk996 pictures of it show both bimetallic strips in good condition and open Attached thumbnail(s) |
bbrock |
Jan 25 2021, 07:19 PM
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#56
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914 Guru Group: Members Posts: 5,269 Joined: 17-February 17 From: Montana Member No.: 20,845 Region Association: Rocky Mountains |
took the sucker apart and retested the resistor pack without being hooked up to motor, values are: Low- 1.5 Medium- 3.4 high- 1-1.5 @Superhawk996 pictures of it show both bimetallic strips in good condition and open Where are placing the probes to measure resistance and do you see any resistance specs on the resistor pack? My is stamped 2.5 ohms for the low speed resistor and 0.75 for medium speed. Measuring resistance with probes on each end of the resistor, I got 2.5 ohms on the nose for the low side, and 1.1 ohms on the medium side. The medium sides was higher than what was stamped but works okay so I think those stamps are ballpark. |
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