I have a 2003 tahoe with electronic dual climate zone and at the 60 to 89 degree range it is all cold (like its on 60) and at 90 degrees it very hot. There is no in between. I can switch the air from head to feet to defrost and all those work fine, the only problem is there is no intermediate temperature. I talked to a former mechanic who said it could not be the mix door actuator because the air was changing from head to feet to defrost all fine. This is really been bugging me and I cant seem to figure out the problem