Intermittent Blower Fan, Now Not Working

[Jokeness]

Vehicle: I have a 2001 Explorer Eddie Bauer with the EATC.

Problem: The blower fan was working intermittently until one day it stopped altogether. When it did work, all speeds worked.

Resources: Haynes 36024 Repair Manual, Multimeter (I am a meter n00b though), this forum, and lots of coffee.

Things I've tried: I swapped the Blower Fan Relay in the PDM with another one in the PDM that had the same part number (iirc it was the Starter relay) and the car started, but the fan still didn't work.

I checked voltage on the pink/white wire on the fan and had 11 volts, same for the orange/black wire.

Backprobed (paperclips and wires with alligator clips) the orange/black wire on the fan and grounded it and the fan came on (one speed only).

Connected the orange/black wire on the fan to the black wire on the controller and the fan ran (one speed only).

Ran the diagnostic on the EATC and came up with 888, no problems.

Conclusions: The fan works and has power getting to it. Where to go from here? 2 observations: the hood strut leaked right on the side of the controller plug on the plastic (it didn't appear to have gotten into the plug/wires though), and before the fan became intermittent the lights on my radio stopped working, possibly unrelated but since the radio sits right above the EATC I wonder if they share a ground. The manual I have doesn't have a great wiring diagram.

Suggestions?

 

[koda2000]

With the blower fan turned on high and the the blower not working try tapping on the motor with a hammer. If it comes to life your fan motor is bad and will need to be replaced. Even if it doesn't start working it doesn't mean the blower motor is good. If you have power and ground to the blower motor it should work.

Electric motors often will work intermittently when they are worn out. Eventually they stop working completely.

 

[J_C]

I don't have a good wiring diagram for that but from what I gather, the blower motor controller module (on the firewall) grounds the fan, through a transistor, and that transistor frying is the most common fault of the system and seems likely to be the problem with yours.

If you have fair soldering skills and a > ~40W iron with a stout tip (not conical), you can swap that transistor. Otherwise for $40 something (price varies) you can get a new entire module at Rock Auto or Amazon, etc. Even some local auto parts stores have them at reasonable prices but local prices can vary wildly, these used to cost more than they do now.

https://www.amazon.com/Premium-Resi...1-Automatic-Temperature-Control/dp/B075SXVNT3


More info about swapping the transistor in my post here:

1996 Eddie Bauer Explorer Blower Motor Only works On High

https://www.digikey.com/products/en?keywords=MJ11028

I could be wrong since yours (presumably) does not work on high speed, which I had thought bypassed the transistor and only needed the high speed fan relay, but again I don't have a good wiring diagram for that to know for certain. If there is a relay on your motor controller module that is another possible fault fixed by replacing the controller module.

 

[koda2000]

I don't have a good wiring diagram for that but from what I gather, the blower motor controller module (on the firewall) grounds the fan, through a transistor, and that transistor frying is the most common fault of the system and seems likely to be the problem with yours.

If you have fair soldering skills and a > ~40W iron with a stout tip (not conical), you can swap that transistor. Otherwise for $40 something (price varies) you can get a new entire module at Rock Auto or Amazon, etc. Even some local auto parts stores have them at reasonable prices but local prices can vary wildly, these used to cost more than they do now.

https://www.amazon.com/Premium-Resi...1-Automatic-Temperature-Control/dp/B075SXVNT3


More info about swapping the transistor in my post here:

1996 Eddie Bauer Explorer Blower Motor Only works On High

https://www.digikey.com/products/en?keywords=MJ11028

I could be wrong since yours (presumably) does not work on high speed, which I had thought bypassed the transistor and only needed the high speed fan relay, but again I don't have a good wiring diagram for that to know for certain. If there is a relay on your motor controller module that is another possible fault fixed by replacing the controller module.

I agree that the blower motor control module is a fairly common failure point. I takes the place of the blower resistor on the manual HVAC system. As I recall reading on this forum when the module goes out the fan typically still works on HIGH speed, so it might also be the motor itself. I'd pull the motor out and test it to be sure as both replacement parts are roughly equally pricey.

 

[Jokeness]

I forgot to mention I pulled the motor out and connected it directly to the battery and it ran.

 

[koda2000]

I forgot to mention I pulled the motor out and connected it directly to the battery and it ran.

In that case, perhaps your issue is with the control module. If you're up to the task, some here have taken them apart and soldered them/replaced transistors as needed. Also examine the electrical plug to make sure it's clean and not burned.

 

[J_C]

Here is "a" diagram but it is for a similar era Crown Vic not an Explorer.

It should be pretty similar though different wire colors seem possible, for example it has no pink/white wire. A Crown Vic also use a fairly similar looking yet different part # controller module.

I am unfamiliar with the settings available on the EATC head unit, but if it has a way to set max fan, and a relay on board the controller module, doing so should result in voltage (relative to chassis ground) on pin #2 of the controller module connector, where there wasn't any with the fan set to a slower speed or off. You could also check for resistance to ground on pin 1 of that connector. It should always have low resistance to ground. Keep in mind that the wire harness connector may (or may not) be a mirror image of this pic:

 

[Jokeness]

Sorry for the late reply, new job with lots of hours. I ordered a new blower motor controller from car parts dot com and installed it today. So far it has solved the problem. Thanks everyone for the help!