Blower motor works only when it feels like it

[zx150]

Got an '04 Astro AWD and the blower motor only works some of the time. Seems to kick on if I hit a huge pothole, passenger kicks the underneath of the dash or whack the blower motor. Does this sound like a blower motor on the way out or a wiring problem?

On a different note I replaced the engine thermostat and found a small vacuum lime under the hood that was broken off from something. I've been having issues for years with the dash vents not really working. Had the transmission replaced at the Chevy dealer the week after the warranty expired and that's about when these issues started. The end of the vacuum line has clear silicone smeared on it so it looks like the dealer *tried* to fix it...lol

Where does this vacuum line go?

[doyoulikeithere]

Sounds more like a corroded connection or a bad ground that makes your blower intermittent.
Check the connector under the hood on the blower isnt dirty, also the connector on the back of the blowers speed switch on the dash.
I'm not sure where to re-attach the vac hose, but someone here will chime in.

[LiftedAWDAstro]

The blower motor is probably bad. To test it, when the blower doesn't come on when it's supposed to, open the hood and wiggle the connector at the blower. You can also test the plug for voltage. You should see 12.5 volts or more with the blower selected to high. I have replaced the blower in my 98 and my 03 for the same symptoms. Make sure it isn't a single speed related issue as this would indicate the resistor pack is bad. It contains the high speed relay as well.

For that vacuum line, do a search here for defroster diverter valve and you will see info on how to fix.

[zx150]

It does this at every speed. Will wiggle the wire and check it out. Thought it was the connector in the dash but it only responds and comes back to life when you whack the motor, if you whack the dash nothing happens.

[Drummernaut]

You can differentiate between a wire/connector problem and a motor/connector by applying 12.5V to the motor connector directly. If it runs smooth there may be something wrong with the wire/connector. If the motor is still intermittent and you are a bit handy you can disassemble the motor and clean the commutator and brushes, or see if there is anything left of the brushes.

I have fixed many( well.... at least 5) DC car blower motors this way. Others needed new bearings or bushings.

[MountainManJoe]

Blower motor is likely on it's way out. Be careful ... It'll take the resistors with it! (not cheap)

[zx150]

Thanks for the help guys! Appears that the red plastic connector has snapped at the housing, looks like the best fix is a new blower.