Hi all, I hope someone can help. My wife's envoy has been having issues with the heater and air conditioner control. The outdoor temperature shows 20 to 50 degrees, and then the ice posible light comes on. This effects your ability to get the air conditioner to come on and only the heat comes on, even thought you have adjusted the temp "wheel" to your desired temp. The actual ambiant temperature is over 100. Is this an issue with the temp gauge sending unit, and if so is this easy or hard to fix. What else could it be. Your help is appreciated, it is hot here in Dallas.