Automotive Repair

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Blower not blowing (self.auto_repair)

submitted 2 days ago by Fondots to c/auto_repair

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I got in my 2007 4runner (SR5, V6, 4WD for you AutoZone types) to go to work last night and got nothing out of my vents. Made for a chilly commute to work.

I'm not mechanic but I know how to Google a problem and can generally be trusted with a wrench or screwdriver if I know what the problem is, so I narrowed it down to 2 most likely issues- bad blower motor (duh) or a bad relay.

So I came home, tapped on those parts with a tiny hammer (allegedly sometimes that works) and poked at some things with my multimeter.

It looks like I'm getting 12v at the connector to the blower motor, so am I right in thinking that's a pretty sure sign that it's the motor itself that's bad? I'd think that if my problem was the relay I wouldn't be getting anything there.

Just kind of looking for a little sanity-check, already ordered a new blower and it should arrive sometime today (prime same-day shipping is a magical thing sometimes) but should I be steeling myself for a cold drive to AutoZone to pick up a relay?

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[–] [email protected] 2 points 2 days ago (1 children)

12 volts across the 2 pins would indicate a good ground.

If you disconnect the plug you should be able to read the motors ohms. It should be low. 2-8 ohms. Open would indicate solid state circuits or open motor Solid state would probable show something in the high K or probably the megs. Open open would be bad windings.

If the current source feeding the motor is weak, then testing it with an incandescent automotive bulb would let you test the resistor circuit. Resistors would vary the lights brightness. No light and the issue is that way.

I’m trying to think in my head what could give a false positive 12v indication on the pins. Poor contacts,…

[–] Fondots 1 points 2 days ago* (last edited 2 days ago)

And as these things always seem to go, it looks like it was something stupid

Despite plugging and unplugging it about a dozen times last night, and wiggling everything around while poking my multimeter at everything I can reach and scratching my head as to why the fan wasn't blowing when all the numbers look perfectly normal

I just plugged everything back in to give it one last once-over before the new motor arrives in a few hours, and the fan roared to life.

I think I'm chalking this one up to just poor contacts. It wasn't working a couple hours ago when I started fucking with it again today, and it is now and all I've done since then is unplug it and plug it back in a handful of times.

The contacts look to the naked eye about as clean and corrosion-free as any I've ever seen, but I guess they could be worn down a bit (though I can't imagine why they would be) or it's just thermal expansion/contraction doing what it does. If it goes out again I guess I'll swap in the new motor since I'll have it on-hand now, and hopefully that'll solve the contact issue if it comes up again.

Thank you for letting me bounce some thoughts off of you. Didn't really think about checking the resistance on the motor itself, and while that didn't directly reveal the cause of the issue, it is what made me unplug it and plug it back in one last time, so I guess "task failed successfully"

EDIT: Nope. 99% sure it's the blower itself again. Must've shken something loose temporarily while I was messing with it or maybe bringing it inside to look at warmed up some gummed up grease or something for it to move because it just wouldn't work from a cold start but did work again after a gentle tap from a hammer, so definitely a good thing I have the new blower coming