Many homeowners are not aware that their HVAC unit can become a source of water damage to their home, especially if their unit is inside the house or attic. The HVAC condensate line can become blocked, causing water to back up into the unit and overflow. This can be easily avoided if the unit is properly maintained.
Most drain pipes for HVAC systems are made out of PVC. Locate the condenser unit inside your home, and you will see one or two PVC pipes exiting the system. A short section of PVC will point upright and may be open or capped.
Before doing this maintenance, turn off your unit. Take the cap off the PVC pipe. For the best and safest results, dilute 1 part bleach with 1 part warm water. Using a funnel, pour the mixture in the PVC vent pipe. Capture the mixture when it exits the pipe outside to avoid contaminating your yard or the surroundings. To avoid any pooling of the bleach mixture along the line, follow the bleach mixture with a gallon of warm water about an hour after the initial application.
This application should not be necessary more than twice each summer. Performing this maintenance more could damage the condensate line.
This video shows the basics of how to do the above maintenance.
If your condensate drain line is clogged, the following video shows one way that you can clean it out using a wet/dry vacuum. (Note: You can create your own vacuum attachment without having to purchase the one advertised in this video. This is for information purposes only.)
If you are uncomfortable doing this yourself, please call an HVAC technician to help.