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DoctorDave005

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August 12, 2019
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Year, Model & Trim Level
2002 Explorer Sport Trac
I am having some problems with my climate control in my 2002 explorer sport trac. On fan settings 1,2, and 3 there is no air coming from the vent. However, on the high setting, 4, they both work just fine. I read that this can be related to the blower motor resistor so checked that out. It was a very tight squeeze but I managed to get it out of the back of the blower housing under the hood. I inspected the resistor and the wires that connected to it. (detail: the resistor I found was one with several coils and an electrical resistor, not one of the card-shaped ones I have seen online). The connectors were slightly tarnished but certainly not enough to prevent conduction between the surfaces. The resistor itself also was very slightly rusted in couple spots but did not appear to be in bad shape to me at least. Should I still just replace the blower motor resistor to fix this? Or could there be something else that is causing this problem? I would appreciate any insight into this issue before I starting buying parts to fix it. Thanks in advance.
 



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Speeds 1,2 &3 are controlled by relay in bulkhead fuse/relay box, drivers side. High speed (4) relay which is ok is near/under alternator.
Check out relay at bulkhead, maybe this is your problem.
 






Thanks for the quick response David. I checked the relay in the fuse box. I was able to remove the cover to the one for the blower without damaging it. The fuse appears to be almost new and is not tarnished in any way. I suspect it may even be newer as most of the relays in there were stamped as 2016. Any other suggestions? Could it just be that resistor even though it doesn't appear faulty? Could it also be the fan speed control knob underneath the radio?
 






Find another similar relay from the power distribution box and swap it with the one for the blower motor (if the prongs on the bottom are the same the relays are the same). See if that makes a difference. Just because the relay that says 2016 on it doesn't mean it's good.

Other possibilities:
- Bad blower motor control switch
- Wiring issue
- Bad electrical connector
- Bad blower motor resistor

Do you have a volt-ohm meter to test with?
 






I would guess the blower motor resistor is bad. I had this happen on a Taurus a few years ago. Motor worked great on high, but no other speeds worked. Once I took mine out I discovered a little bit of rust on the coils had caused the problem. In the Taurus it was mounted on the blower motor, but I think on the 'Trac is is in the engine compartment.
 






koda2000, I will try swapping those relays and see if that works, that is a good idea. Unfortunately I have not yet invested in a multimeter yet. If it is not the relay I will get a new resistor and see if that fixes the problem. I'll update the thread in a day or so with how it goes.
 






koda2000, I will try swapping those relays and see if that works, that is a good idea. Unfortunately I have not yet invested in a multimeter yet. If it is not the relay I will get a new resistor and see if that fixes the problem. I'll update the thread in a day or so with how it goes.

A multi-meter is a great tool when diagnosing electrical problems. Even a $10 meter from Harbor Freight is better than nothing and less expensive than throwing parts/money at a problem hoping it fixes the issue. I paid about $60-$70 on mine probably 10 years ago and I use it all the time.
 






Thanks for the help and advice all. I tested another relay in the place of the one that controls the blower motor and it made no difference. After that I tried replacing the resistor and that fixed the problem. This was surprising because, visually, there did not seem to be anything wrong with it. Problem solved. I'll definitely invest in a multi-meter so I can avoid this type of confusion in the future.
 






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