Climate Control Unit randomly quit working?

My climate control unit will randomly quit working/no lights or ability to use any of the controls but IF the blower was on for example for heat, it will continue to run. This happens just randomly. Everything may work for several days in a row then it doesn't. There are times it will come on/light up when I start the car but then 5 minutes later go off. At times it may come back on after sitting a few hours, other times it won't. It is not the battery, just put a new battery in 4 months ago when this issue started with climate control unit. Dealership thought the battery was the issue. Within a 5 mile drive the power/lights went out on the control unit. Took it back, they say it's not throwing any codes. When you live in an area the weather changes day to day sometimes every few hours it's important to have a working climate control unit! My rear unit works fine.