AC not always starting - sometimes it does, sometimes it doesn't

[wintersilke]

2004 Vibe, automatic transmission, 2WD, 94k milesOverall I am very happy with this vehicle. Just in the past week however, my wife has noticed that when she turns the vehicle on, the AC will not come on. Neither heat or cool air will come out which makes me think the blower is going. As soon as she hits a bump or small hole in the pavement though, the AC starts blowing at the temperature she set it at, so both the heat and cool are working. Coolant pressure is fine.Anyone else encounter this problem or have a suggestion? From the forums, it appears it is either the blower or the resistor. Can the blower get gunk on the rotor and resist turning but not be actually burnt out?

[sandi65]

I have this same problem...did ou find out what the problem was??

[wintersilke]

Yes...The blower motor, below and behind the glove compartment, had a short at the point where the wiring harness snapped into the bottom of the blower motor. Jiggling the harness while the electrical was connected would cause the blower to turn on and off. The conclusion was that the circuit board inside the motor was losing the connection to the power coming in. I went to a junkyard and got a replacement blower motor for about $70 from a Toyota Matrix.Make a note of this...if you get the Matrix part it will not fit all the way in in the same spot the Vibe part came out of. I had to put in a rubber gasket on the collar of the Matrix blower to take up the room so it would fit. The bolts/screws go in the same way and the wiring harness will fit the same. I made the gasket by putting a 1/4" bead of silicon caulking on the collar and letting it dry for a couple of hours. That was how close the parts are...1/4" difference.When you do take it out, take the opportunity to either replace or clean the A/C air filter. It will substantially increase the amount of air that passes through and make the entire car more comfortable. I decided to clean mine since it was 11 at night when I was doing this. To clean it I used a the back end of a spoon that had a blunted tip (so I wouldn't poke a hole in it) to get the debris out and then blew compressed air from a can to get the dust off it.Good luck.