What would it be

Your reversing valve is not pulling in for some reason. It could be stuck or may not be getting power (24 volts). It could be anything from a broken orange wire ("O") or a bad t-stat. You will have to use a meter to trace it out and find out why it is not working. DrTom4444

It is a new t-stat,I will test the orange wire, thank you

If you wired it wrong when you put in the new stat you have your answer. Some heat pumps use the "B" terminal and others use the "O" terminal and use either a blue or orange wire. When the heat pump needs "O" for cool then the "O" terminal is used while others use the "B" for heat. You probably have the "O" type as they are more common. DrTom4444

I put in a h-well pro5000, red-rc, yellow-y, blue-c, brown-o/b, green-g, white-aux

I put in a h-well, red-rc jump r,yellow-y,blue-c,brown-o/b,green-g,white-aux

When you put it on cool you need to check between C (common) and "O" and see if you have 24-30 volts. Make sure the brown goes to the "O" terminal out on the condensing unit. The "Y" just pulls in the contactor and the "O" decides whether it is in heat or cool cycle. Some heat pumps are wired with "B" instead of "O". You can turn off power to outside unit and when power is put to "O" you will hear a click if it is working. There is a solenoid on reversing valve so you need to see where the two wires from the solenoid go and test the voltage there where it should read 24-30 volts when calling for cooling. If not you have something wired wrong. DrTom4444