I have a 2005 Chevy Silverado 1500 with the auto HVAC system that I can turn the fan speed up to high when I turn the HVAC on but if I turn it down I can’t get it back up to high it goes to low.The temperature control ***** also are acting weird and that I can’t change the temperature unless I previously sent it and then turn the whole system off and then turned it back on. When AC is turned on it will be blowing cold air and then start blowing hot air at a random point and then stay hot until I either turn the truck off and turn it back on or turn the HVAC off for a while and then turn it back on. I am also seeing that with the doors that the air comes out of sometimes I can change that and sometimes I can’t. Any help would be appreciated I can’t figure this thing out. I have heard a knocking behind my dash if that helps any. Thanks.