Climate Controls

BLiND · September 18, 2001

Hey all,

I'm new to the board, and have a quick question:

When my climate selecter is in the off position, air still blows out of the selected location (floor, panel, etc.) and also when I run it at the 3/4 fan setting occasionally it will blast at full power for a second or two and then settle back down, should I rebuild the fan speed selector? oh and when in defrost mode with the fan off, my compressor still cycles on/off, and when driving at highway speeds using the a/c I feel a bucking motion from the truck whenever the compressor cycles on, is that normal?

1997 GMC Sierra California Special edition, black/gray, trim removed via hairdryer and WD-40

Kania2k1 · September 20, 2001

First and foremost, welcome to the site. Back to your problem. Is the switch on Vent or Recycle? I haven't seen the dash for a 97, so I'm not really sure, sooner or later somone with one will be along, have no fear. As to the fan issue, I think it's not anything to worry about. At least it doesn't stay at full speed the whole time, and it shows that it can still go to full speed. I think it is somewhat normal for the "Bucking" fealing because the compressor is taking a little belt power away from the other accessories. I'm not sure about the defrost issue though. Maybe there is some sort of pressure that the system keeps. I don't know, maybe this help, or maybe I'm talking out my ###. Hopefully someone else can back up some of my rambling. Again, welcome.

CR500 · September 20, 2001

My 96 Z71 does the same thing. I was on a different forum and a bunch of guys had the same problem. The GM trucks allow fresh air to blow through the floor vents all the time when the fan is turned off. You'll notice the faster you go the more air comes in. What is happening, is that something is allowing the system to go from floor vents to dash vents. Mine will start coming through the dash and then slowly go back to floor. If you turn the vent selector knob to floor, it should go back to floor. Mine does. I didn't do anything for mine. I think the people who built our windshield wiper circuit board built our climate control system also.