Please help - Central unit stopped but this internal fan stays on.

Hi all
Well unfortunately our central air unit (outside unit) stopped working yesterday. Go figure when it's 103 outside. At any rate, some friends suggested to check the fuses. I will go out and just buy new 50 amp fuses.

However we notice a constant fan noise coming from behind the filter that is underneath our furnace. It's loud enough to know that it wasn't like that before (to any of our knowledge). It's been "on" all day.

At any rate, I don't know what it is. Attached is a pic of what is emmitting the fan noise.

Any help would be appreciated. The thermostat is off.

Thanks.

 

The black box in your photo is a condensation pump, not a fan. Water from the air conditioner drains into the bottom of this unit and when it’s full it will turn-on and pump the water outside. These pumps have an internal safety float switch. If the pump can’t pump the water outside it will shutdown your condenser to prevent additional water from building up which could cause flooding.
As a test you can unplug this pump from power, pull out the white PCV pipe and put in a bucket. This will let water drain from AC unit and should let system turn on. Caution, if the air conditioner works again don’t leave the PVC pipe in the bucket because it may quickly overflow.

Good Luck

 

PS, I forgot to mention that you may also have to drain the water out of the bottom of the pump so that the internal float switch can drop down, (open) it's contact.