Diagnosis of problem with air conditioner / cooling fan

Hello,

I am in need of some assistance with the diagnosis of an air conditioner & radiator fan problem on a 2002 Cavalier LS Sport.

The air conditioner blows cold air while the car is moving most of the time. At idle, the air conditioner will suddenly blow warm or even hot air.

At idle with the air conditioner off, the car idles fine. When you turn the a/c on, it runs a bit sluggish. Also, ever 5 seconds you hear what I assume to be the compressor cycle on/off.

After a little research I discovered that this problem could be a faulty radiator fan motor.

Tonight, I pulled the electrical plug to the fan and found that I had voltage to the plug when the engine was running with the air on or off. I then ran wires direct from the battery to the fan and could not get the fan to spin. This obviously tells me that the fan motor must be bad.

My real question is.....should I really have voltage to the fan when the a/c is off and the car is just started? I thought the fan should only turn on when the engine got warm with the a/c off. I started the car and pulled it in to the garage and then shut it off before I did my testing so I don't think that would classify as getting the engine warm.

If for some reason whatever temp sensor that controls the fan (with a/c off) wasn't working property and always had voltage going to the fan, perhaps that is what burned out the fan motor. Is that a far reaching idea? (Or should I quit trying to over-think it and just replace the fan motor and then see what happens.)

Any thoughts would be appreciated. Thanks

Update: I am now wondering if the voltage was always present even with the AC button off because I may have had the fan in the recirculate mode. The AC light is lit in this mode even when the AC button is off. I am hoping that is the case but won't know unless I test it again. :-(

Well here is the conclusion....

Related to the update section at the bottom of my last post......I tested the voltage again at the plug and found that when you are using recirculate, the fan wire still has voltage even if the a/c button is off. When you take it off recirculate with a/c off, the voltage goes away. I was glad to see these results because after my first (incomplete) test, I thought I always had voltage to the fan which meant I had a sensor issue also. (I was testing in recirculate mode.)

Anyway, I replaced the fan motor tonight (23.99 + tax) and everything works fine now. It took me about an hour to do the job with a good chunk of that trying to finagle the fan assembly in and out of position. Overall, it was a fairly easy job for me and I don't have very much mechanical ability.

Hope this post helps someone with the same problem.

Good work.....had no idea that the the fan would run with the the recirculate button on, either....

Should have power when engine has reached a certain temp, the A/C is on, or in some cases when a PCM code is set....

I don't know if this is just with General Motors or all cars. I will check my non-GM car the next time I pop the hood.