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Discussion Starter #1
  • Help! I just got a used 2004 Pilot EX and the rear blower motor didn’t work. I replaced the resister and it works now. But ever since there’s a horrible noise from the speakers when the rear blower is on. The interference noise is loud and not affected by the volume control. It’s a constant roar if the climate control is on “auto” (the rear blower fan at a medium speed). If I activate manual rear control, the noise (and fan) speeds up faster and rises to a crescendo and stops. If I put it back on “auto,” the noise comes back and as the fan speed lowers. I am thinking it’s a ground somewhere but don’t know where to start. Could it be related to the new resister I installed? Thank you for any help.
 

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  • Could it be related to the new resister I installed? Thank you for any help.
Unless you did something else with electrical parts, that sounds like a pretty good bet.

I'm just guessing, absent any solid information, that you bridged / shorted at least one side of the controller circuit when you replaced the thermistor. I used shrink-wrap on the legs of the thermistor to avoid doing that. Still guessing, but your symptoms are consistent with motor noise rippling back into the power circuit, where it was previously isolated by the controller's electronics.

Suggest you pull the controller again and see if either of the thermistor legs are touching anything metallic, or if your solder has flowed out where it shouldn't be. Unsoldering and removing the thermistor would be a definitive test - if the noise goes away, you found it.
 

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Discussion Starter #3
Thank you for the quick response! Unfortunately, I have limited “electrical” knowledge. I’m a moderately “handy” mom of 3 high school /college drivers trying to juggle auto issues with a lot of you tube videos, etc. What is the “controller” you are referencing? I’m including photos of the resister because I’m not sure what you mean about the “legs.” I have a video that I wish I could post that demonstrates the sound it makes, but I don’t think I can upload it.

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Thank you for the quick response! Unfortunately, I have limited “electrical” knowledge. I’m a moderately “handy” mom of 3 high school /college drivers trying to juggle auto issues with a lot of you tube videos, etc. What is the “controller” you are referencing? I’m including photos of the resister because I’m not sure what you mean about the “legs.” I have a video that I wish I could post that demonstrates the sound it makes, but I don’t think I can upload it.
My apologies. I assumed that you had disassembled the part in the pictures and soldered a new component inside.

The part that I called the "controller" is what you called the resistor. Honda calls it a transistor; its job is to control the power to the fan to give you the right speed, and to provide a safety feature that prevents over-loading the fan circuit and creating a fire hazard.

If you simply removed the old part and replaced it with the new one, then either the new one is defective, or the electrical circuits aren't working properly.

Try this:

1. Pull the plug off the new part and wipe off all the contacts on the plug and the part with a q-tip or similar. Check the wires leading into the plug to make sure there are no cracks in the insulation or bare wire showing. If so, the wire will need to be taped to prevent bare copper from touching. Re-connect the plug, making sure that the plug is firmly seated onto the part, and that the part is firmly seated into its mounting hole. I think its an insert / twist movement to mount the part. Test it again.

2. If that doesn't fix it (it probably won't, but you might get lucky), remove the new part and put the old one back in. Test it again to see if the noise goes away. The fan will stop working, of course, but eliminating the noise will give you clear evidence that the new part is the problem - you just got a bad one. If that's the case, return the part for a replacement, and re-install.

3. Hopefully, this will fix it, but if not, its likely that there's another electrical problem in that circuit. You'll need a mechanic to track that down. You can decide whether the lack of AC is more or less annoying than the noise, and wait for a convenient time to get the car in the shop, if you decide to pursue a fix.

Good luck!
 

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This won’t fix your issue, but there is a lint screen about a foot (towards the gas pedal) from the rear blower transistor module. I’ll bet it’s covered with lint and needs to be vacuumed off. It’s likely the old module failed due to lack of airflow across it.

If replacing another blower transistor doesn’t fix the noise in the speakers look for loose ground connections around where the transistor module is inserted as well as the blower itself. I believe there is a similar access panel for the motor left of the front passenger’s left foot.

Good luck and keep us posted on what you find.
 

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Just thought of one other thing. Did you replace it with a resistor module or a transistor module? I believe the LX uses a resistor module while all other trims (EX, EX-L) use the transistor module.
 

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This thread was started a long time ago - but I just had the same thing happen. The problem is the inexpensive Amazon-sourced replacement part. Once I removed it, the sound stopped. I repaired the original per the other instructions on this forum and it has been fine ever since.

I just joined the forum today; so this is my first post!

Randy in Texas
 

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Welcome to the forum. Glad to hear you resolved the issue.
 
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