Our ac will be working great and then all of a sudden stop blowing cold air, room temperature air will blow instead which heats the house up quick. If we turn the unit off for an hour or two it normally starts to blow cold air again once it's back on. We've checked to see if the unit if frozen under the house and it is not. There seems to be no rhyme or reason to why this happens. We have a baby on the way in 3 weeks and would love to know what the problem is before he gets here!

Well, your compressor is shutting off. There are many reasons this could be happening. It could be a short in the wiring. There could be a blockage of some kind. It could also simply be a thermostat issue. My advice would be to contact a repair person, as it doesn't sound like a problem you may be able to diagnose/fix yourself. Good Luck.

Probably something happening in the outside unit, try washing the outside coil (condensing unit) take a water hose and wash from the top down(don't spray motor) This is the best thing you can do for a air conditioning unit besides replacing the filter. What happens is if the condenser coil gets dirty it does not cool the refrigerant and the pressure builds up higher and causes the compressor to work harder and may overheat the compressor, these compressors have a built in temperature actuated overload that will shut down the compressor until it cools off and starts running again.
Another thing to check is the fan motor , is it failing? The bearings in the motors may need to be oiled if oilable and the motor may be failing due to overheating.
Last , if the thermostat is programmable, is it programed correctly? Hope this is helpful, Mike
By the way Congratulations!!

My husband just went under the house to check the ac unit and it appears that the air handler is frozen. He believes this has been what's causing our ac to go from cold air to room temp. over and over. What do we need to do to keep the air handler from freezing

Like already stated cleaning the coil is a very good idea and if it is your air handler like you stated the filter probably needs changed and clean those coils you can buy a self rinseing coil cleaner for the air handler just shut the unit off and spray wait ten minutes and turn unit back on. If that does not do the trick you might need to have someone put guages on it it might be low on refridgerant.

My air condition unit fan is running but there is no cold air on in the house