I'm getting 4 flashing lights from my furnace, meaning an open limit switch. It is -40c today so I'm wondering is it overheating and turning off just because it's having a hard time keeping up? Or is there an actual issue?
Check your filter for good airflow to keep cool. If possible, check you a/c coil to see if it's plugged or clean for good airflow. These things are free. If not, you may just have a bad limit switch.
Updated on February 7, 2018
By Dan Robbins