The blower gets 14 volts but won't run. Clearly the blowers bad, right? So I replace the blower. New blower gets 14 volts but won't run??? Used existing ground wire and positive so its not the ground... This doesn't seem complex so what's going on here??

Are you talking about the cabin fan or the engine compartment blower?

Does the blower run when you give it 14v when you are holding it?

quote Originally posted by Arachnyd: Used existing ground wire and positive so its not the ground...

Exactly what do you mean by that? The ground wire should be 0, not positive.

How are you testing that you get those 14 volts?
Just looking at the installed volt meter in the car?
Probing from the 'positive' to ground?
Probing from the 'positive' to the ground wire at the connector that would be connected to the fan?

Remember the voltage does not do the work, it has to have current to back it up. With your voltmeter, measure BOTH sides of the motor when the negative lead of the voltmeter tester is connected is to ground (body or negative terminal of battery)
If you measure the 14V on both sides, the ground is probably bad. Remember though, you must make the measurements WITH THE LOAD CONNECTED - this is the mistake most people make. When you take a sweater off, those little sparks are thousands of volts, but won't run your blower - not enough current behind them. Keep at it- you'll get it!

I ran into a similar issue recently that had me stumped. When I put the volt meter across the wires, I would get 12v as expected. However, when I put the accessory on those same wires, nothing would work. Got a test light out instead of the volt meter. The bulb in the test light was enough load to find out that the wire would conduct 12v, but could carry no load. Test light would never light up.

Ditch the voltmeter, and try a test light. It worked for me!

Thanks for the responses- this is the cabin blower.

If I connect from the ground of the blower to the ground wire that attaches to it, I get 14v or so, so since I'm using the existing ground wire it shouldnt be the ground.

I'm using a volt meter.

If I connect the blower directly to the battery it works. So its getting the voltage but not the amperage required to run it. While I'm oh-so-tempted to run a freaking wire straight to the blower with a relay triggered by the 14v existing current, I like to do things right.

so what does this sound like? I replaced the relays, replaced the HVAC control unit inside the car, and replaced the blower.

Sounds like we are talking about problemmatic wiring here, right? Or possibly something in the resistor for the blower (probably the next replacement point) but that should only effect the "low" settings because my understanding his "high" bypasses it- so at what point are the "high" and other lower settings at a common-point? Just the original wiring?

The blower motor has two wires on it. Black is ground. The purple is positive.

Hook the fan up with both wires, and turn on the fan switch to high with the key ON. Stab you voltmeter RED probe into the purple cable (make sure you are through the insulation into the wire) or slide the probe in behind the black boot around the spade connector. Then connect your BLACK voltmeter probe to a ground other than what the fan is using. We want to measure voltage with everything hooked up.

If you have voltage on your meter but no fan, your ground is bad.
If you have no voltage, you have faulty wiring on the power side.

Last question: Do you heater controls work? IE...can you hear the ducts moving when you change between heat/defrost etc??

[This message has been edited by brownc00 (edited 05-16-2012).]

quote Originally posted by brownc00: The blower motor has two wires on it. Black is ground. The purple is positive. Hook the fan up with both wires, and turn on the fan switch to high with the key ON. Stab you voltmeter RED probe into the purple cable (make sure you are through the insulation into the wire) or slide the probe in behind the black boot around the spade connector. Then connect your BLACK voltmeter probe to a ground other than what the fan is using. We want to measure voltage with everything hooked up. If you have voltage on your meter but no fan, your ground is bad. If you have no voltage, you have faulty wiring on the power side. Last question: Do you heater controls work? IE...can you hear the ducts moving when you change between heat/defrost etc??

Ducts do work, and when I turn the AC on the radiator fan kicks on.
What about the alternative-
I have voltage on the meter but no fan, but the I've confirmed the ground is good? Does this sound like in-line corrosion or something funky? Where woudl the faulty wiring be?

Ignition on. Fan on HI
Run another ground anyway for a test. Connect to the body and the ground side of the blower motor.
If no joy, run a lead from the +ve side of the battery to the positive on the blower motor. If the motor is good, then one (or both) of these tests will make it run. Notice I did not say to remove the extra ground while testing the positive....although unlikely it is possible both are bad. Make sure you connect the power and ground to their correct terminals, or things could get warm. ....

quote Originally posted by Arachnyd: Ducts do work, and when I turn the AC on the radiator fan kicks on. What about the alternative- I have voltage on the meter but no fan, but the I've confirmed the ground is good? Does this sound like in-line corrosion or something funky? Where woudl the faulty wiring be?

IF you have voltage at the meter, you have a bad ground. Same thing holds true on that. Just because you get voltage reading on the meter using that ground, doesn't mean that the wire is good. It might support that little load of the meter, but not the large load of the fan. Disconnect it and run ground from something else and fan should work.

quote Originally posted by brownc00: IF you have voltage at the meter, you have a bad ground. Same thing holds true on that. Just because you get voltage reading on the meter using that ground, doesn't mean that the wire is good. It might support that little load of the meter, but not the large load of the fan. Disconnect it and run ground from something else and fan should work.

I have good voltage at the meter... tested the fan by connecting it to a battery. it worked. I tried running a separate ground. Still didn't work. Hooked a automotive bulb tester to it, light didn't light, but even through the bulb I'm getting voltage, so I've never seen this before in my life but somethings killing the amperage but preserving the voltage. It seems fishy. I wondered if I have volt meter problems, but its showing just under 14v with the car running and 11.3 with the car off (but in acc setting). 0V with car completely off. Checked the fuses, swapped it out anyway... haha.

Leaning towards issue with some sort of relay or some mystery parts I'm missing. Doesnt it just go from HVAC controller -> relay -> Fan? Therefore if the controller, relay, and fan are all replaced it can only be a wiring issue, but what can that issue be?

quote Originally posted by Arachnyd: I have good voltage at the meter... tested the fan by connecting it to a battery. it worked. I tried running a separate ground. Still didn't work. Hooked a automotive bulb tester to it, light didn't light, but even through the bulb I'm getting voltage, so I've never seen this before in my life but somethings killing the amperage but preserving the voltage. It seems fishy. I wondered if I have volt meter problems, but its showing just under 14v with the car running and 11.3 with the car off (but in acc setting). 0V with car completely off. Checked the fuses, swapped it out anyway... haha. Leaning towards issue with some sort of relay or some mystery parts I'm missing. Doesnt it just go from HVAC controller -> relay -> Fan? Therefore if the controller, relay, and fan are all replaced it can only be a wiring issue, but what can that issue be?

Power comes from fuseblock, to the HVAC controller, to relay to fan. On mine, the wire from the fuesblock to HVAC unit would get voltage, but no amperage. This caused the power to drop off and not allow me to change the air flow (heater, defrost etc) under any load. Turn your fan on high and see if those still work. It's a long shot, but could be the same issue.

[This message has been edited by brownc00 (edited 05-16-2012).]