Troubleshooting E5 Error Code on Advent Air 13.5K Air Conditioner

Updated 07/25/2026 | Published 07/20/2026

Question:

Cut the power to the unit climbed up and cleaned the coils and blew them out with a blower went back inside and turned the breaker on and power to the thermostat and it started showing E5

asked by: Joseph A

Expert Reply:

Hi Joseph,

An E5 error on an Advent Air 13,500 BTU unit like the # ADV87QR typically indicates a communication error between the rooftop unit and the thermostat/control box.

Since the error appeared immediately after cleaning the coils and restoring power, I'd start by turning the power off for 5-10 minutes to let the control board reset, turn the power back on and check the communication cable between the rooftop unit, control box, and thermostat in case it came loose while cleaning the coils. Make sure none of the wires were pinched by the shroud when it was replaced as well. You can also test the wires to make sure the thermostat has 12V power running to it.

If everything appears connected correctly and the E5 code remains, the issue could be a faulty control board or a failed thermostat.

Is this a new AC unit or thermostat that you're having trouble with?

expert reply by: Claire H