I have two eight year old York heat pumps on my house. The smaller unit is for upstairs and we have noticed lately that in the AC mode the temp upstairs is higher than we set the unit for. We set it for 75 and the temp rises well into the low 80's. We can hear the fan running in the house and air is coming out of the vents. We notice that if we shut off the thermostat and remove the batteries, then put it back together and restart it from the thermostat it will often work again. This does not always work but at some point it will begin cooling properly again. This is the first time we have had any issue with this unit. The filters are new.

Thanks for helping!