Looking for options and opinions and know this is the best place for both. Heater and AC work. Blower speed works as well but won't change off vents. Selector switch has more resistance than expected but it won't change positions. I'm assuming the switch but not sure how to get the part. Is it just the one or do I need to change the whole thing? Defrost would be nice on these brisk winter mornings in the country. Thanks