When I have the a/c on, the aux heat is switching on. Why?

Question

I have a heat pump and the a/c is set to 73-74 degrees. After it runs a cycle, I will feel hot and check the thermostat and the AUX heat has kicked on. It is 90+ degrees outside! Why is it doing this? I had the a/c unit serviced a few weeks ago and the guy said it was fine, clean coils, etc. Do I need a new thermostat?

Answer 1

is the thermostat for your heat seperate from your AC?  if so, it's working perfectly, it dosn't matter how hot it is outside, the thermostat only cares how cool it is inside.  when it get's too cool the heat turns on.  i would suggest just turning the heat pump off alltogether for the summer.

Answer 2

there is nothing wrong with your unit when the inside air is lower than the set on the thermostat the heat cuts on so that it can reach the temperature that's set

Answer 3

Best idea I have is to check the thermostat and make sure you have it in cool mode.  If in auto mode it will heat when needed and cool when needed so if you have it set at 72 and the AC brings the temp down to 71 it will automatically go to heat mode and bring the temp back to 72.  If you have a cool night and the temp goes below 70 aux heat will probably come on.

Answer 4

yes a new thermastat should take care of this not to mention lower you electricity bill aux heat is very expensive to run and is meant only to supplement your air source heat pump this could leat to damage of your electric elements replace thermostat if problem persists thermostat is miswired verify new installation i think it will solve your issues