I'll try to keep this somewhat brief. I bought my current home about a year ago here in the PHX area. I have two AC units and two thermostats, one for upstairs and one for downstairs. The upstairs thermostat presented its problem last year when summer kicked in and we just dealt with it. I would have a set schedule on the thermostat with temps changing at different times of the day. We would find that it would get quite hot, go over to the thermostat and it would say it was 80 degrees upstairs (where we were) but that it was set to be at 76 or 74 deg depending on the time. I'd manually tell the thermostat to drop the drop setting several more degrees hoping the AC would kick on, it wouldn't. I'd turn of the "cool" so that neither cool nor heat was on and then turn it back on to cool, AC wouldn't kick on. Sometimes it would kick on outside, I could hear it go, but minutes upon minutes later nothing was coming out. I'd continue to jack with the thermostat for up to minutes before finally it would actually come on and start blowing cool air, usually within 30 sec of it turning on outside. I recently went to Lowe's and got a new thermostat figuring something was just wrong with the last one. I replaced a Honeywell thermostat with another Honeywell one. I got it all hooked up as instructions showed and it works...however the same problem is there. Eventually I'll get it to work again by removing the thermostat off the wall for several minutes, putting it back on and turning the fan to "on" instead of "auto" and after a few minutes of the fan blowing I'll turn the setting to "cool" and the AC will come on, then a few minutes later turning the fan to "auto" from "on" and it will work as it should....and this happens about 6 out of 10 times. Sometimes the fan will shut off after putting to "auto" and I have to start the whole process over again. Anyone with any advice or thoughts as to what is going on? I'm guessing it has to do with something outside on the AC unit since it's happened the same with two different thermostats? Thanks in advance for your help.