Hi Bob
Sorry we did not get to you sooner. So to help need to know if you have a manual or automatic HVAC?
I will assume you have an auto, so this is what you do
On the control panel simultaneously press and hold floor,mix and defrost ATC panel will blink release all buttons. Then panel will blink until it completes test, then codes will be displayed in a numerical form.
Post those code numbers and I can tell whta is going on.