What this code means
The Blueridge BMKH M3 system service manual identifies F4 as outdoor condenser middle-pipe sensor open or shorted.
Safe checks
- Confirm the thermostat is on, set correctly, and calling for heating or cooling.
- Check the air filter and visible return-air path for obvious airflow restrictions.
- Record the displayed code or flash sequence before scheduling service.
First step
Record the code, avoid repeated reset attempts, and schedule GreenFlow service.
Frequently asked questions
What does F4 mean on a BLUERIDGE BMKH42MC?
The Blueridge BMKH M3 system service manual identifies F4 as outdoor condenser middle-pipe sensor open or shorted.
What should I safely check before scheduling service?
Use only the visible, non-invasive checks listed on this page. Do not open equipment panels.
When should GreenFlow handle this code?
Call GreenFlow if the code repeats, the equipment is locked out, heating or cooling is not restored, or the condition involves gas, ignition, pressure, wiring, a motor, or a control board.