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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#1
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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 |
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 |
Mar 23 2021, 08:19 AM
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#2
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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 |
UPDATE: finally got around to installing this new refurbished box, well not quite , i tested it first, and i only get one speed, same as before , and this is a new fan, resistor pack was tested for proper values, etc. ok, first step i thought must be the controls, so i connected 2 other controllers that have cleaned contacts, and were tested before i bought them from the p.o. , same results. the only explanation is that the wiring for the other 2 speeds is compromised, only the white/green wire allows for acompleted circuit once the slider attaches to that contact it is connected to. If i move the wire from the low to high connector then the fan will turn on but not on the other 2, so tonight i will experiment with a couple temp wires from the controls to the fan, i do think for some reason - So the power goes from the fuse box to the fan and is hot from #8 fuse, and on with ignition. the circuit is completed when the lever is slid to right and the feeler contacts the selected connector and completes the circuit, low is just one wire, medium and high will have 2 feelers touching either #1&2 or #2&3. thus completing the circuit thru the different resistors , thru those and to the fan motor. and one else ever have this senario? |
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