My car's AC fan sometimes won't come on. I think it's the blower motor, what do you think?

Today my car’s AC fan wouldn’t come on at any speed setting, only to come on later in the day… what could it be? Well, I don’t think it’s the fuse (otherwise the fan wouldn’t come on at all,) it’s probably not the blower motor resistor either.

I suspect it’s the blower motor, let me tell you why:

My house fan kinda behaves like that… when the blower motor is about to die, sometimes it won’t come on at all, other times it will work just fine, before finally dying, months later. What do you think of my diagnosis? Is the logic sound?

Addendum: I suspect the blower motor for two other reasons:

Even when it works fine, a couple of years back it started making a mildly audible chattering/clattering mechanical sound, I suspected then that it was probably degrading.

Also, this happened a couple of months ago in the winter when it wouldn’t come on then came back on as if nothing had happened.

I would check the connections with a simple meter. While you are at it, giggle the wires a little.

You can also bench test the fan with a simple 9V battery. Testing is generally much cheaper in the end than making assumptions.

what kind of car is this ???

The next time the blower motor doesn’t operate, reach under the passenger side dash and tap on the blower motor with the handle of a screwdriver. If the blower starts working the blower motor requires replacement.


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The car is a 2007 Corolla.

Bench testing the fan with a power source is a good strategy but this problem happens intermittently, so it can be tricky.

Since it is so intermittent, how about hot wiring a lightbulb to the fan’s connector so you know when it is supposed to be on - just leave it in circuit while you’re going about your business. If it stops running and the lightbulb is on, you know to replace the fan motor.

My daughter has an 03 Corolla and she had the same problem about three or four years ago. I pulled eh blower motor and found some contamination on the armature. I could not get that motor apart so I cleaned the armature through the brush holes until I got the contamination off of it. It has worked ever since.

Thanks for the tip! I’ll check the armature and that light-bulb idea is going to be very helpful.

I’m scratching my head as I had the same issue with 05 Kia Picanto. I followed keith suggestion (thank you!) to pull the blower motor and found contamination or some black dust inside the motor. you’ll have to remove the fan cover to see the motor. I then used WD electrical contact cleaner and spray on the holes and have it thoroughly dried. So far, it is working fine :wink:

Why not replace it? It’s not that expensive. You could also pull the resistors and clean the terminals. Check all grounds including under the hood.