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2003 lincoln navigator blower fan issue

5K views 11 replies 3 participants last post by  CatSkinner 
#1 ·
my 2003 lincoln navigator rear fan is always on when the climate control is engaged in the front. It seems to be stuck on mid speed and will go to high but not off (even when the overhead and rear control fan are off).

Could it be the blower resistor motor?

Thanks.
 
#2 ·
I don't think so. Normally the resister will cause it to lose speeds. Most times its a varied resistance path to ground. So the blower is getting a path to ground with it switch in the off position so even if you unplug the rear resistor and the blower shuts off it could still be shorting to ground after it.
 
#3 ·
Interesting. I will unplug the rear resistor and see if it stays on (it should not as you stated). When the rear blower is on, it is not in the lower speeds but rather at the three speed level. You can switch it to go higher but not lower and it will not shut off. It will only turn off if the front controls are in the OFF position.

Any other suggestion to isolate the problem?
 
#5 ·
Removed the rear resistor (disconnected) and it indeed stopped the fan from running all the time. With the resister disconnected I can switch the fan to high only. No lower speeds (but again the fan does not run all the time). Sounds like the resistor is bad??
 
#6 ·
Purchased a new rear resistor and no change with the problem. Same as before.....disconnect resistor and fan stops and only works on high from the front controls (both the overhead console and rear console) but is not on all the time. Place new resistor in (just like the old one) and fans stays on almost high speed and can switch to high from all the controls.

Took a moment to reflect on spending $24 for nothing and now asking does anyone have any advice on the solving the problem.

Thanks.
 
#7 ·
I never said if it stops when unplugging that it was bad. I suggested inspecting for signs of corrosion which can cause a path for the blower to get its ground. Since it stops when it's unplugged and works on high the problem should be before the resistor.
 
#8 ·
R-clar. Thanks for the help here. Where would you start now that it looks like it before the rear resistor? By the way, the plug itself looked ok....no burn marks etc but it is hard to see into the plug.

I was thinking maybe the overhead console fan switch? You have suggested maybe short/grounding issue? Could it be the atc unit itself?

Thanks for helping troubleshoot this issue:)

Jeff
 
#10 ·
Played with it a bit more and found that if I barely plugged the resistor in it would allow for a low speed fan from the overhead/rear controls and would go to off by the controls. The fan still did not work on speed 2 but did work on speed 3 and to speed 4. I thinking the plug may be bad. Very hard to see in it and much less to clean it (corrosion?).

Funny, the car only has 48K on it and always was parked in a garage. Seems odd the plug is bad.

Any thoughts out there or go with the plug replacement?
 
#11 ·
checked some more on this issue. I disconnected the fan and checked the incoming hot. it is always hot (regardless of fan switch setting). If the fan is unplugged the resistor does not have any power to it. Interesting one of the coils in the resistor gets red hot. When I use a light meter on one side of the coil the light is dim and as I travel across the red hot coil it gets dimmer and then to no light.

Still searching for the problem. Thanks for any help out there!
 
#12 ·
Power to the fan is always hot as long as the fan relay is energized, the speed is controlled on the neutral. The relay is controlled by the mode switch. The readings across the coil makes sense, once again, because it's on the neutral side of the load (motor), but I really don't think it's supposed to glow. If you were to take the fan to high, you'd get no voltage on the side you are working on. I had a similar issue with a service van from that era, they replaced the switch with the resistor.
 
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