Blower motor not working.......need help.

[1.8TTony]

Ok, so here's what's going on.......I turn on the air conditioner and air does not blow through the vents. Everything else seems to operate correctly. The a/c compressor clutch works, the dryer canister in the engine compartment gets cold. I can hear the vent doors moving when I select different vents, but the blower motor still does not activate.

How do I get the blower motor to work properly? This is what I've tried.......

Removed, inspected and tested #6 fuse in the fuse box located on the side of the dash......it's good. This circuit is getting power.

Removed, inspected and tested the maxi fuse in the fuse box located in the engine compartment.....
It's good. This circuit is getting power.

Removed, inspected and tested the blower motor relay in the power distribution box in the engine compartment.......it's good. This circuit is getting power.

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The following, NOT getting power.

Removed, inspected and tested the blower motor.......it's good. This circuit is NOT getting power.

Removed and inspected the blower motor resistor.......it LOOKS good, I have no way of testing this item, but it does not look damaged nor burnt in any way. The fan speed control knob has four speed settings and since none of the speeds work, I assume the resistor is NOT the problem because the chances that all four resistor circuits going bad at the same time is not plausible. Either way.......this circuit is NOT getting power.

I removed the HVAC panel knob assembly and looked at the fan speed control switch. It looks good. I have no way of testing this knob........this circuit is NOT getting power.

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Tried another thing:

Removed, inspected and tested the a/c control switch. It's good......this circuit is getting power and is sending power when activated.

So, to recap:
No power at the blower motor.
No power at the blower resistor.
No power at the speed switch knob.

Yes power at the fuses.
Yes power at the relay.
Yes power at the a/c panel switch.

In regards to the a/c panel switch, the power SENT from it is a purple wire. I assume this wire is the trigger wire to activate the a/c system and for whatever reason, the a/c system is failing to send power to the blower motor resistor or failing to send power to the blower motor speed control knob.

So what's next?!

 

[J_C]

See attached wiring diagram.

The blower motor receives constant power when the blower motor relay is activated, then is speed controlled through its ground.

Due to this, if there is not 12V on the positive power lead to it, this rules out the blower motor switch (which you could have tested for closing circuit on the various pins (very low resistance) with a multimeter). This also rules out the blower motor resistor, how ever it can fail and have all speeds but High fail to work because there is a thermal fuse there which all the resistor coils go through. That fuse can also be tested for staying closed circuit, though it may have a bit of tarnish on the leads that needs cleaned off for a good test, but as mentioned already you don't need to do this since it's downstream of the motor.

What remains since you have power at the relay, is the relay itself or the wire from the relay to the blower, or the relay isn't being energized. The diagram shows a pink/white wire so I would check resistance of that between the relay socket and the blower motor connector. Should be near zero ohms, or at least 5 ohms or less.

The blower motor does not depend on the A/C system except for the other dash knob, not the knob the purple wire is coming from, since it also works with the heater. It just needs the dash max/norm/panel/floor/defrost/etc switch in any position besides Off, and that grounds the relay coil to energize it. You can test that dash switch with a multimeter, between pin 4 and pin 3 on the switch itself should be near 0 ohms in any switch position besides off. You can also check for a good ground between pin 3 of its connector and any chassis ground point. You can also check for low resistance between the relay coil red/orange wire and the red/orange wire at the dash knob connector.

Don't forget to check for connector corrosion. I should mention that this wiring diagram is for a 2nd generation Explorer and most of my suggestions above are based on it, so I may be wrong about some of the above but your manual HVAC setup and testing should be very similar to this.