A/C Fan Problem


#1

On a recent trip out of state, I developed a problem with the fan on my 2000 Monte Carlo. When I first started the car, the fan would not blow. After a few seconds to a few minutes, the fan would come on. I took it to a mechanic and their analysis said the fan switch was bad. They replaced the switch assembly.



On the ride back home, the fan cut out, along with the cruise control and the little information center display. After 40 minutes, it started up again. The problem has worsened. When I start the car, no fan. It might start up after 10 seconds, 10 minutes, an hour or not at all. If it’s blowing chances are at some point it will just stop. When it is not working, some of the lights on the display are lit, but which lights change as I move the fan speed dial (for example, the recirculate light is lit at speed 3, the A/C light and the outside air light at 4, etc.). Also, when the fan is not working, pressing a button does not change anything (light on, stays on when button pressed).



One last symptom. I found that if I turn the key from On to Off, it may kick on the fan. This doesn’t always work.



Any ideas on what is causing the problem would be greatly appreciated.


#2

My feeling is that the blower motor is bad and the switch diagnosis was wrong to begin with. Generally the blower motor or the motor resistor will fail before the switch does.

Blower motors can also be a hit and miss affair like this, and excessive current draw by a worn motor could probably cause the erroneous readings. Electrical stupidity if you will. Hope that helps.


#3

One other thing to check, my car had a similar intermittent failure due to a failing ignition switch. On my car, wiggling the key a little would sometimes cause the blower to restart. Replacing the ignition switch cured it.