Defroster

I have an 02 Alero, and the defrost doesn't work. I tried turning the knob, and it turns fine, but then I realized. Nothing else works. It always blows the air through every vent, minus the defrost one. Is this a bad knob, or is there a motor issue?

Which engine do you have?

How are the fans speeds? Have you had any work done on the engine recently? You may have an accessory vacuum related problem. The HVAC actuators used for airflow use engine vacuum.

I have the 3.4 v6. I just got the car, used of course, about a month or two earlier. They had to recharge the AC, and it was working for a while. I'm not sure for how long. Also, the fan speeds are fine. They go off, low, and high, etc.

How about the other controls and positions like recirculate and floor, etc?

I would start by making sure vacuum is getting to the actuators. On the 3400 there is a vacuum line coming off the intake manifold (left side) that feeds into the firewall for HVAC. Hopefully the HVAC head unit (climate control unit) doesn't have a problem.

Well if Im understanding what your saying with the other controls, they don't work. The heat/cool knob works, heat wise anyway. The cool is just outside air i beleive, even with the ac button on. The other selector knob, with the different postiions doesn't. It always blows the air through the top vents and the feet vents, even if just one or the other is selected.

I will check on the vacuum and all that later in the day.

I am having the same problem. Mine has the 4cyl engine. The inside/outside air works fine so I am assuming I have vacuum but I can not get defroster at all. No matter where i have the switch set I get air out of the vents.

If I remember correctly, beacuse it has been almost a year now since I've had that problem, it was just that the knob was broken. Its just that the switch is just a piece of plastic that brakes easily...so you just have to get it replaced.

Yellow Eyes, Thanks for the help. The switch felt fine but I tried it anyway and sure enough, it cured the problem.

Yea, it felt fine for me too, whcih is why i least expected it, but GM works ya over again lol.

I actually took it to the shop for them to look at and it cost me like 160 bucks total i think, just to have them look at it and replace it lol.

I took a chance, found a used one for $40.00 and put it in myself. For once things went my way.

Thanks for the belated update on this thread but it has now runs it's course. Now classified as an old thread and no longer open for any further discussion. If anyone else has a similar issue post a new thread.


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