My outside AC unit has started doing something I just cannot figure out. It will run for some time and then cut off. You can hear it when it does so, kind of a hum. Fan not turning, but can hear the unit. If I leave it off for maybe 10 minutes or so I can turn it back on at the thermostat. It will then run again, sometimes for 30 minutes or so, sometimes longer. Then the same thing again. Turn it off, wait, then it runs once more. I was having this problem, service tech came out and checked freon levels, all good, and cleaned the coils in the attic. When it cools it works just fine. Now, same problem remains. Additionally sometimes when I turn the thermostat to cool (electric thermostat) it my take a while to come on. Yesterday it did this back anf forth stuff most of the day. This morning when I turn it to auto/cool it hasn't kicked on at all. Thoughts or suggestions on what I can check? I'm almost leaning toward replacing the thermostat but don't want to just waste money changing things.

Is the outdoor unit an air conditioner or a heat pump? Do you know the brand/model# ? When the fan stops, do you hear a "gushing" sound? If the fan motor is top-mounted in the unit, carefully feel the center of the fan guard when the motor stops. If it feels excessively hot, the motor or capacitor (or both) may be bad. If your digital thermostat has a recycle time delay (most do), that may explain the lapse before the system restarts.

I think that the "gushing" sound you mentioned may be correct. I should have noted, the fan motor was replaced about two months ago, but I do not believe the capacitor (cylindrical in shape) was replaced. Yes, I do feel more heat than I suspect I should coming from the motor. It is an outside central air unit, an Amana if I am spelling that corectly.

How recently was the service contractor there? If the original issue was never resolved, there should be some obligation on their part to investigate further. On the surface, it sounds like a fan motor problem, but other possibilities linger. The motor is still in-warranty after only two months.

Agree with kc It should still be under warranty. Also I am wondering if it may be a capasitor problem if you are say it was not changed with the motor.

OK, so outside fan is shutting off, is compressor still running? Is inside unit fan still running? I also agree with KC13, most electronic thermostats will have a five minute start delay for ac.

Thanks for all the responses. When the unit shuts down, that is when the fan stops, the compressor does continue to run. This may sound crazy but with the unit running if you spray it with a hose and release the heat so to speak it will run forever and cools perfect... figured this out because it was raining and it never shut off once and whe I tried the hose every so often it keeps on going. So I know, or think I know, the motor is a the least working. I'm going to change the capacitor and see, unless someone has a better suggestion for me.

May still be capacitor, cheap to replace. I would try it first. Also, make sure outside coil is very clean and that no fins are bent over. Sounds like your motor is just overheating and cutting out on internal overload. If cleaning the condenser coil and changing capacitor doesn't work, looks like you will need another new motor. Good luck and please let us know how things work out.

Also was the motor replace with the same? Maybe the rpms are not right. This would cause the motor to over heat.

Thank you to all for the info. Changed the capacitor, five bucks later so far so good.

Great!!

My window unit turns off after about 20 minutes can you tell me what could be the problem?