stuck in cooling mode no heat what is wrong with it?

Hi. Check you element, t-stats, and fuses. Make sure you are getting proper voltage to the unit. You could only be getting 120V which is enough for the unit to run but not heat. You need 240 v to heat. If all of that checks good you could have a bad control board. I have attached a tech sheet on a similar unit. try to run diagnostics and see if you get any error codes.