I have a heat pump A/C unit. It will run fine for a day or two, then just stop working. I switched from the old mercury t-stat to an electronic one, didn't fix it. Two technicians from two different companies can't fix it. The thing is, when it stops working, all you have to do to start it again is switch it from cool to off and switch the fan from auto to on. In about 30 seconds, the fan will start blowing. Then immediately switch from off to cool and the fan from on to auto and it starts blowing cold air and will work fine for another day or two.

I have a Payne outdoor AC unit that makes a metal banging sound on start-up??. It is less than one year old and was installed with a new evap coil (not sure of the correct item) in the house above the furnace. I thought the banging sound was due to the unit jumping off the concrete slab it sits on when starting, maybe it should be bolted to the ground. I watched it, and this is not the case. The fan also tends to have an up and down noise when running, sort of like a zoom, zoom, zoom, zoom sound, instead of a steady "zoom" sound that I hear from neighboring units??. The last issue I noticed is that when sitting outside when it was hot last week, the unit was running and then some other mechanical motor noise kicked in?? Last night I blocked off one of the kitchen floor vents trying to make more air go into the upstairs bedroom. Ironically, later that evening, I went outside and the AC was running very quite (best sound I've ever heard from it) and was totally amazed. I'm not sure whether my closing the kitchen vent had anything to do with making the AC unit run smoother or it could be that the temperature outside was cooler. Anyway, when I was admiring the new quiet sound, all of a sudden, the outdoor unit starts buzzing like a basketball late shot buzzer for a few seconds and then went off. It did this a few more times before I had to go in. Can someone please tell me what is the problem, thanks?