I'm getting blower fan noise through my speakers

[Mustang Matt]

When my blower motor is on (AC on or off) I hear pulses come through my speakers. If I turn the stereo off or the fan off it instantly goes away.

Where should I start troubleshooting?

 

[MonzdaCon]

I think it might be a grounding issue. do you have a system in your car?

 

[Mustang Matt]

Nope. All factory speakers with an aftermarket headunit that I've had for a while after someone stole the factory one.

 

[Tzar177]

do you have a sub and/or amp?

 

[Mustang Matt]

No sub. It's only using the factory amp if there is one.

 

[jonridinhi]

Dose the noise change withe the different blower speeds?

 

[Mustang Matt]

Yes

 

[jonridinhi]

Check your ground on your radio and blower. One of them is not grounding suffenently to the frame. The only other possibility is that your grounding kit is not functioning properly. It sounds like your blower is grounding out to your radio but not threw the whole system. Same thing happens with your alternator sometimes. I had that issue.

 

[Mustang Matt]

Well there's another piece of info that is probably relevant. I though the problem was gone but it came back.

Every once in a while my blower motor completely dies. It will work for months and then it will die for a minute, a day or a couple of weeks and then it will come back on and work fine for a while.

The blower circuit consists of the motor and a relay and all the wiring in between right?

 

[jonridinhi]

Well there's another piece of info that is probably relevant. I though the problem was gone but it came back.

Every once in a while my blower motor completely dies. It will work for months and then it will die for a minute, a day or a couple of weeks and then it will come back on and work fine for a while.

The blower circuit consists of the motor and a relay and all the wiring in between right?

Your motor or any electronic device will "die" or stop working if there is no ground or a lose connection. You can have all the power in the world going to it and if it has no ground it is useless. Do you have a multi-meter? Yes the blower power comes from the battery threw a harness and a fuse or relay then to your switch then the electric motor then to ground. there is a break in the system somewhere. You might have to check the resistance all the way threw the harness. Do you have any other electrical issues to go with this like the lights are dimmer ect.?

 

[Mustang Matt]

No other electrical issues. I do have a multimeter but I'm not real proficient with it.

 

[jonridinhi]

Unplug the plug going to the blower motor. There shouls be 2 wires. (if more that is the different speeds) There should only be one ground. You need to see which one dose not get voltage the whole way threw the cycle of your contol knob. That is your ground (I bet the wire is proboly black.) Then you need to flip to the setting on you multi meter than looks like an up-side down horseshoe and that will check ressistance. if your tips touch it should read 0.00 or if they are apart ten it should read OL. The put one end to your plug and put the other to a stable ground somewhere in the cars frame or negative terminal if your leads are long enough. Post what you get.

 

[Mustang Matt]

Alright I'm going to pull it apart Thursday and check it out. I don't even know where the blower motor is located. Is it behind the center bezel somewhere?

 

[jonridinhi]

If memory serves me correct....
Behind the glove box.

 

[jonridinhi]

Alright I'm going to pull it apart Thursday and check it out. I don't even know where the blower motor is located. Is it behind the center bezel somewhere?

Update???

 

[noliftinitspeed]

its probably a magnetic field interference. the two wires for the speaker and the blower motor may have been rubbing each other and wore the plastic down and now there connected. Trace you wires for your blower motor and your speakers, see if they are touching.

 

[Mustang Matt]

Been busy with the holiday, might have a moment here in the next couple hours. Having some friends over tonight so I'm trying to get the place presentable. This is the coolest 4th of July I can remember in STL.

I can hear the fan behind the glove box so I think you were right about that.

 

[Mustang Matt]

I tried using my multimeter. What an incredible tool in the hands of someone that knows how to use it. Unfortunately I am not that guy (yet)! lol

The problem is, I need to test it when it's not working and today it's working. The blower motor seems like it's having difficulty coming on. It's slow to spin up and making a bit of noise. I would have liked to disassemble it all and see if there was anything obvious that was a problem but it looks a bit involved to get it out. I might give it a go this weekend. Anyone have a spare blower motor for sale?

I looked around at other wires for any obvious problem and didn't see anything. I need to figure out how to remove the headunit. I think I need a flat radio removal tool of some sort.

My multimeter has autoranging and when I tried to measure resistance it kept moving the decimal and then giving me a loud beep. I couldn't get anything but 0L to show up.

I found a plug that turned the blower off when I unplugged it. I think it's for a thermometer possibly. It had 12V going to it and seemed to change which wire had 12V when I changed the fan speed settings.

 

[Mustang Matt]

Final update: I replaced the blower motor and solved all three of my problems.
1. The motor comes on 100% consistently
2. The fan speed is much faster
3. The interference in the speakers is gone

I started to replace the entire blower box but that proved to be quite difficult, so in the end I just swapped the actual motor which was held in by three screws.