I have a tempster air hanndlerr. My thermostat screen was blinking and I couldn't adjust the temp, so I turned the breaker on the air handler off then back on and the screen went blank. I tested and there was no power at the thermostat. I called a tech and he bypassed the breaker saying I can do without because I have an outside breaker. It worked for a little while after he left then qiit. There is nno power on the wires to the thermostat again. The breaker outside was not tripped.