I have a Rheem central air conditioner unit which suddenly stopped blowing cool air (AC). The outside unit (compressor) seems to be working since it kicks on. However, the air blowing inside the house is only room temperature air. I made sure the blades were turning in the right direction on the outside unit and the pipe with the insulation is cool to the touch. What could be the problem?

Stick a thermometer in one of your supply registers and let us know what it reads. Also indoor temp. My bet is that your condenser(outdoor unit) is extremely dirty and needs to be cleaned(as easy as using a garden hose and spraying fins clean) or you have a leak in the system and need a service call to find leak and recharge system.

You say outdoor unit is running, at least the fan, but do you also hear the compressor running?

The temp is reading 81 on the thermostat unit for indoors. I'm not sure if I'm hearing the compressor running outside or if it's just the fan. Seems a bit quieter than the other outdoor unit on the other side of house. The air that is being output from the outside unit in question seems cool compared to the warm air being output by the other unit that is working. Does that mean something?

Sounds to me like your compressor is not running. Could be a bad capacitor or you might have another issue. Compressors are not an easy diagnosis without being there to see what's going on. Might want to have a tech come out and look at it for you.

You've got to find out if compressor is running first. If you don't feel qualified to determine this, you should call for onsight pro. Please let us know what they find.

Before you call for repair check the filter on your furnace. If you haven't replaced it in a while sometimes that is the quick easy fix.

Msmewiththat is correct. Checking and changing filter is always a good first move to make. However, I believe if your filter were that plugged up you would notice ice buildup on lineset. Or at least feel cool air coming out of registers(just less of it). I suggest replacing filters at least twice a year, or even every three months.

Thanks for all of your help. The compressor was working but turns out when I took off the cover to the outside unit, I noticed that the capacitor looked as if it had a meltdown. So I called a pro and he agreed that the capacitor had to be replaced. There was plenty of freon and the compressor was fine. The filter was clean since I replace it every 2 to 3 months. What a relief! Could have been an expensive venture. But once again, thanks for all of your responses. I sure learned a lot.

I am happy that you found resolution. Stay cool :)