Some systems can gravity feed water from a unit but in some cases an HVAC system must use a pump when it is too low for gravity to remove the water.
When a condensation pump stops working water will over flow and spill into a basement or any place it is located at.
Most often a leak will be a kinked line or possibly a bad condensation pump.
Often dirt and mold builds up with-in a pump and the lines that run out of a home. If these lines become blocked the pump will not be able to remove the water.
It is also possible the pump has gone bad and needs replaced but be sure to check for any blockages in the lines first.
A common method to clean a pump is to use compressed air in a the lines and blow out any debris.
Pouring bleach into a pump once a year will also help in keeping the mold build up to minimum.
If there is no noise coming from the pump it is likely bad and needs replaced. Be sure to check if power is going to the pump.
Replacing a unit with a new one is not difficult and falls into the DIY category. As always call a professional if in doubt.
Replacements are measure by the HP for example 1/30 HP or 1/50 HP along with voltage. Most all unit will be 110 voltage.
Look for the name-tag on the old unit to get a replacement.
Condensation Pump on Amazon
Little Giant 554425 VCMA-20ULS Condensate Removal 1/30 HP Pump with Safety Switch
A pump can be located anywhere near a unit so water gravity feeds into a holding tank.
Once the holding tank reaches a certain level the pump turns on and pumps out the water.
The line coming from the HVAC system is often a 3/4 in PVC pipe but can be any hose attachment.
The line pumping water from a home is most always a clear tube.
Replacing a unit is simply a matter of removing the water lines, placing them on a new unit, and plugging it in.