2001 Mountaineer Blower Issue with Digital Climate Controls

[Mountaineer302]

We have a 2001 Mercury Mountaineer 5.0 (same as Explorer) with the digital climate control system. The blower motor is new and has been tested. The blower control module which takes the place of the blower resistor is also new. The problem that we are having is that the blower will not run at any speed setting or in any mode. Can someone please point me in the right direction to diagnosing what is wrong here?

 

[Centaurus5.0]

Corrosion inside the plug that goes to the blower? Bad Ground?

 

[Mountaineer302]

It appears that the blower control module is energized when the key is on even is the HVAC system controls are turned off.

The connectors are clean.

 

[Mountaineer302]

It seems the transistor is not turning on or not being driven to turn on.

 

[1998Exp]

You need to understand that the controller is "low side" (provides ground). The power is a constant +12V, supplied through a fuse (#2 in the box under the hood) and a relay (#9 in the same box). Check the fuse first. If good, turn the blower on through the EATC (speed does not matter), unplug the blower and check the voltage at the two pins. One (pink/white) should be steady at 12V. The other (orange/black) goes to the controller and will probably read 0V. If you don't see 12V, it's probably the relay. Swap with another relay in the box to check.

 

[Mountaineer302]

So, the controller should always have 12v when the key is in the on position even if the inside controls are turned off?

The voltage does not change on the blower side of the connector.

 

[1998Exp]

Please do yourself a favor and read carefully:

The controller does not control the voltage. It controls the current - it behaves like a variable resistor on the ground side of the blower. If you don't have background in electronics, it will be difficult to explain in detail how this thing works. Forget about the controller for a moment and first check that the blower gets +12V on the pink/white wire. The voltage on the other wire (the one that goes to the controller) doesn't mean anything when the blower is unplugged.

If you haven't done so yet, check the blower itself by hooking it directly to the battery. It should run at full speed.

If the blower is fine and receives +12V on the pink/white wire it's time to check that the controller works. Plug it back and back-probe both contracts with the blower turned on (or poke through the insulation). If you see constant +12V on both wires, it shows that the blower winding is fine, but there is no current flowing through it due to a problem on the controller side. Could be the controller itself, disconnected wire between the blower and the controller, between the controller and the EATC, or possibly the EATC itself.

 

[Mountaineer302]

Thank you for giving some great explanations. They are greatly appreciated.

The blower is only a few months old and does work when wired directly to the battery.

I will check or recheck the other things you just mentioned.

 

[Mountaineer302]

I do have some car electrical and electronics knowledge but am no expert. I'm used to dealing with blower resistors and conventional HVAC contols with knobs or levers etc.

Blower does not receive any voltage via pink/white wire on any fan speed setting with key on.

 

[1998Exp]

I do have some car electrical and electronics knowledge but am no expert. I'm used to dealing with blower resistors and conventional HVAC contols with knobs or levers etc.

Blower does not receive any voltage via pink/white wire on any fan speed setting with key on.

It's back to my original advice: check the fuse, and if good, the relay.

 

[Mountaineer302]

We had power from the relay and to the controller. The controller ended up going out again. I think it shouldn't be energized when the key is on. Instead it should only receive power when the HVAC is on. But at least it seems to be functioning normally now.

 

[LoquetusofBorg]

If that is a newer blower motor as mine was the terminals on the new fan are opposite of what the originals are. Try disconnecting the power supply from the fan itself and then insert 2 small screwdrivers or paper clip on each side of the power plug form the motor, then use alligator clips from the fan power plug to the fan itself, then turn your rig on and play with the polarity of the fan hook up, (switch black to red sort of thing with the alligator clips). Unless you bought your fan from ford the polarity of the new motor will be different.
Loquetus

 

[Mountaineer302]

Interesting. I'll have to look at that.