I have a KIA Optima 2012 SX. When I drive the car for a while with the AC on, it stop blowing cold air. The only way to remedy it is to stop and restart the engine. Another situation when this happens is when stopped (at a traffic light or drive-thru etc.) but this is remedied by moving again. Living in Phoenix where it's very hot in the summer (114 yesterday ), having this behavior is a miserable experience. This issue only happens when it's hot outside. I've never experienced it at night. Any suggestions would greatly be appreciated.