Blower Motor Not Working

[sunshine31]

My a/c has not been working so we added R134a yesterday and it fixed the problem just like it did last summer. Once I was finished I left the a/c on high when I shut my car off. This morning when I left for work it was too cold so I turned it to the "off" position. On my drive I decided to turn the a/c on and make sure it was still getting cold at which point nothing happened, absolutely no air (hot or cold) was blowing out. I kept turning it on and off and at one point the a/c did start working again at which point I turned the fan speed to low. A few minutes later the blower completely quit working again. Nothing works at any speed, any position regardless of heat or a/c. Absolutely nothing is blowing out of my vents. I can hear something that sounds like opening and closing when I change the position/type of a/c/heat but the other than that the only sound is a "shhhhhhh" when I turn it to the off position. Can anyone please advise me where to start on diagnosing and fixing this issue?

[jdl]

What is the model year? I'd check voltage and ground at the blower motor connector. If you have good voltage and ground at the blower motor, with blower control turned on, suspect the blower motor. If your missing voltage or ground, backtrack the circuit.

Check applicable fuses.

[sunshine31]

It's a 1997. And it's definitely ok about the double post. I'm just happy that someone replied.

[shorod]

Does your Taurus have the manual (knob) controls or the electronic climate control? The manual controls use a blower motor resistor network to control blower speed. Because of the resistor network, it's a bit difficult to measure power and ground accurately. But, at high speed, the resistor network should be bypassed. An open in the thermal fuse of the resistor network would explain the lower fan speeds not working, but would not explain high speed not working.

If your Taurus has the electronic controls, there is a solid state blower motor controller that uses a transistor and PWM to control fan speed rather than a resistor network. These are a bit more challenging to troubleshoot.

As JDL mentions above, the place to start is by setting the blower motor to High speed and checking for power at the blower motor. I'd recommend using a test light versus a multimeter so that you're providing some load on the circuit. The high input impedance of a digital multimeter could indicate voltage even if there is a bad connection in the circuit which severely limits the amount of current that can flow. However, the load from a non-powered test light will require some current carrying capacity in order to light. It's not all that uncommon for the connector at the blower motor resistor to melt and not allow a good connection.

-Rod

[sunshine31]

It is manual (knob) controls that operate the heating and cooling system of the car.

[sunshine31]

What do you think is the most likely culprit since absolutely nothing is blowing? I got it to come on for just a few minutes this morning by repeatedly turning the switch on/off. Once it came on I turned the fan speed down to the lowest setting but within a couple of minutes it was back to not working at all. I was going to try banging on the bottom of the blower motor (seriously read to try this) but I don't have a tool to get the three bolts off that are holding the cover on it. I've read that some people have had theirs come off/on dependant on hitting bumps on the road but to the knowledge this was not the case this morning.

[jdl]

The link is wiring for manual hvac. It is possible you have automatic hvac? You can see the wire colors and fuses. Check not only the fuses, check the fuse circuit for voltage. One fuse circuit is hot all the time, the other goes hot with the key on.

We can throw parts at it, if want, but, I don't like to do that. If you can't do a little testing, I'm not sure how to help?

[sunshine31]

Thank you. I will be sure to check out the link and see if I can gain a better understanding of what may be happening.

[sunshine31]

I am not sure what an automativ hvac is

[jdl]

http://s7.postimg.org/6v4bbx4d7/manual_hvac.jpg

Did that link show up for you on the previous post, It didn't show up me, I can't see it?

[jdl]

http://s16.postimg.org/bodoiz40l/automatic_hvac.jpg

This is automatic hvac, I'm not sure which one you have?

[sunshine31]

I haven't tried opening it yet but it shows up for me as an attached thumbnail.

[jdl]

http://s30.postimg.org/m9krrthyp/eatc.jpg

If your hvac controls look like the picture, it's automatic, otherwise it is manual. Like the other person said if knobs instead of push buttons, it is manual.

[sunshine31]

It is manual then because my control panel definitely has knobs and not push buttons

[shorod]

Since when the blower stops working, no speeds work, I'd suspect either an issue with the blower motor itself or an issue with the blower motor relay. Per the factory wiring diagram for the manual control, the blower motor relay is part of the circuit at all speeds. For high speed the fan speed switch just shorts the ground terminal of the blower motor to ground. Since High speed doesn't work either, this rules out an issue with the blower motor resistor. You might also note that according to the diagram, when the low blower speed setting is selected there is no ground path for the blower motor, so don't bother using the low speed setting during your diagnostics.

So when you are able to get to the blower motor terminals, and at a time when the blower is not working, confirm whether or not you have power to the blower motor. If you have power, the issue is most likely with the blower motor.

If there is no power, the issue is most likely the blower motor relay or an issue with the fuse connection, 40A fuse 11 in the engine compartment fuse/relay box. First though, measure for continuity through the switch to ground. Use the High speed setting for this. Once you confirm you have continuity, you can rule out the switch and connection to the switch. If we were talking a GM product, I might be more inclined to suspect the fuse connection. But that hasn't been a common issue with Fords that I'm aware of, so the relay would be the prime suspect in this instance. Determining if you have power to the blower when it fails to work is key to properly diagnosing this though.



-Rod