The AC was running fine. Then it stopped. No error on the thermostat. Breaker is on. But the system will not start.
Then you notice the water.
What happened
Your system has a float switch — a small device attached to the condensate drain line or sitting in the drain pan beneath the evaporator coil. When the drain line clogs and water backs up into the pan, the float rises with the water level. When it reaches a set point, it cuts power to the system.
This is not a malfunction. The float switch is a safety device. It shuts the system down before the drain pan overflows and sends water into your ceiling, walls, or floor. Without a float switch, a clogged drain line causes water damage. With one, it causes an AC shutdown — inconvenient but far less expensive.
What to do
- Confirm the float switch is the cause. Look at the drain pan inside the air handler. If it has standing water in it, the drain line is clogged and the float switch tripped.
- Clear the drain line. See our post on how to clear a clogged drain line — vinegar flush or wet/dry vacuum from the outdoor end.
- Drain the pan. Use towels or a wet/dry vacuum to remove the standing water.
- Once the water level drops, the float switch should release and restore power to the system. Some float switches reset automatically. Others have a manual reset button.
- Turn the system back on at the thermostat and confirm it starts.
If it starts and runs normally, the float switch did its job and the problem was the drain line. If the system does not restart after clearing the water, the float switch itself may be stuck or the clog may not be fully cleared.
If your system does not have a float switch
Florida building code requires float switches on systems installed in attics and elevated locations where an overflow would cause water damage. If your system does not have one and the air handler is above finished space, have one installed at your next service visit. It costs very little and prevents thousands of dollars in water damage.
Call (727) 477-3256 if the drain will not clear or the system will not restart after resetting.