#1: Locate the condensate drain.
The condensate line from your HVAC system drains condensation created by the system. It usually looks like a white PVC pipe and is located on an exterior wall, going from the inside to the exterior of your home or building. Sometimes it’s located near the system’s condenser. Once you find it, see if the water inside is frozen. If it is, it simply won’t drain, and the system will shut itself off.
#2: Clear the drain.
Before you attempt to clear the drain, turn the furnace off at the fuse box. Next, attempt to melt the condensation. You can do this in a few different ways. The easiest and usually the quickest way to do this is by pouring hot water over the drain until the ice inside melts. It is important to remember to never pour boiling water on the pipe, as this could damage or even crack it. You may need to complete this process a few times before things melt. If it is not raining or snowing, you can run a hair dryer via an extension cord and use it to warm the line. You can also place a space heater near the drain and run it until things melt. Don’t ever leave an electrical appliance unattended outside, and never use it if there is moisture coming from the sky! If the temperatures continue to remain at freezing, you may need to repeat this process a couple of times to make sure the condensate line stays clear.
#3: Turn the furnace on.
Once the water inside the drain is melted, turn the HVAC system back on at the fuse box and things should be working as normal. If not, and you’re sure that the drain is clear, you may have another issue that needs to be diagnosed by an experienced HVAC specialist.