My central ac unit is working but no air comes out of the vents. I turned it off for a couple of hours, turned it back on, and it started working again. Now, the same thing is happening again.

its look like blower problem , 1st check blower speed controller, check blower motor , check its ball bearing etc , its does not have any link to external unit .

My unit was working fine for a couple years but now it won't evaporate. It still cools fine but it also collects about 16 ounces of water every hour and then shuts itself off until I drain it. I'm wondering it the evaporative mechanism it broken some how.

1 make sure any air or fan vent is clear of lint and dust
2 move the ac further away from wall
3 possible compressor temp sensor gone bad requiring a tech
hope this helps

Reset the furnace by turning it off and waiting 15 seconds to turn it back on.

Yes, it must be vented to the outside, even if you're using central AC, too. The reason being is if you don't vent it to the outside, the hot air and humidity that normally goes thru the duct and out the window, will stay in the house and your Central AC will have to run longer and harder to overcome this rise in heat and humidity. In addition, the room that the portable AC is in, will get extremely hot & humid.

Hope this helped you. Please let me know. Thanks.

IT SOUNDS LIKE YOU HAVE A BAD COMPRESSOR OR A DEAD SHORT SOME WHERE IN THE UNIT

Turn central on fan only and let it run. You probably have a leak in the coils. It will defrost after a couple of hours and start working again. My ac man said turning it on fan only instead of turning it off will help it defrost faster.

DOES THE HOUSE FEEL DRIER IF IT IS 80 OUTSIDE WITH ALOT OF HUMIDITY THE UNIT WILL RUN FOR A LONG TIME TO REMOVE THE MOISTURE(HUMIDITY) OUT OF THE HOUSE BEFORE TEMP DROPS DRAMATICALLY IS THERE WATER COMING OUT OF THE DRAIN PIPE OUTSIDE

Try first cutting system power for a couple of minutes, even from main. With some luck it can be enough to reset the system, as it looks like a problem with the control board. The control board has also a coin battery and a reset bridge on it , but to access them you need to take apart control unit. Try fist turning off main power switch for 5 minutes or so.